The tendency of a saved person to commit sin, repeatedly, is because of lack of fear of God, and lack of fear of God's displeasure,  that leads him eventually to fall out from the mercy of God,  who will chastise the person and bring him back to his fold.  Though the salvation is not lost, yet the chastisement becomes inevitable and, therefore, God brings upon the person chastisement, until he is corrected.  Man's backslidings will themselves reprove him, and pave the way for his alienation from God.  The consequences of sin make a person miserable. In order to keep aloof from sin, which is evil, every saved person's soul should worship God, in spirit in truth, and praise Him, and pray to Him incessantly, so that he remains within the fold of God. 

Revelation 3:4-5 You have a few names even in Sardis who have not defiled their garments; and they shall walk with me in white: for they are worthy. He that overcomes, the same shall be clothed in white clothing; and I will not blot out his name out of the book of life, but I will confess his name before my Father, and before his angels.

The Bible does not leave a person without help. It also provides remedy. A note for backsliders to come back to the mercy of God. He will heal you.  God wants backslider to come back and be in his fold, so that He will shown mercy upon him.  God has no pleasure in any believer staying in sin.  He is longsuffering and waits patiently for His child to come back.  If an earthly father has pity on his child coming back with dirty clothes, it is worth meditating,  how much more our heavenly Father has compassion on backslider. He waits patiently to receive his child back in to his bosom with infinite love. His love is more than the earthly father, whose story Jesus narrated in a parable, showing how that father received prodigal son, in to his bosom, when the son repented and came back to his home.

Few verses that will help us to meditate on backsliding and God's
chastisement and the return of backslider:

Life after backsliding is miserable to the backslider just as the prodigal son experienced, when he fought with his father, and went far off, with his share from the property and spent entire money, ate the food that is given to pigs, and returned to his father, when he found himself, helpless. Backsliding is not just committing sin on a day and asking forgiveness, but it is when a saved child of God turning away from God to seek his own will.  Backsliding in a saved child of God can occur when the child of God falls in to sin and becomes slave to it, or when he does everything according to his own will and his will takes precedence over God's Will.  It is rebellious nature in man that makes him rejecting God's will or his pride overtaking him when he thinks that he can do everything without depending upon God.   It is when a child of God thinks that God's purposes in his life are of no avail, but he has wisdom to manage his own affairs.  It is when a saved child of God thinks that he no longer needs God, but he can attain a place in heaven through his own good works, or wisdom. 

Isaiah 55:7 Let the wicked forsake his way, and the unrighteous man his thoughts: and let him return unto the LORD, and he will have mercy upon him; and to our God, for he will abundantly pardon.

Our God is long suffering and has patience to wait for the sinner to repent of his sin, and backslider to return to him.  God has no pleasure in sinner dying in his sin.  He has abundant love to pardon any one of any sin.  There is only one sin that is unpardonable and that is blasphemy against Holy Spirit; any other sin is pardonable by God. Return to him.

Hosea 14:4 I will heal their backsliding, I will love them freely: for my anger has turned away from him.

God rejoices when a backslider returns to him and asks for forgiveness. The Bible calls backsliding as a disease and God says he loves the one, who returns to him, asks him forgiveness and depends upon him.  God loves to heal the backslider his disease and he says his anger is turned away from him.

1 Corinthians 3:3 For you are yet carnal: for while there is among you envying, and strife, and divisions, are you not carnal, and walk as men?
1 John 1:9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
Hebrews 7:25 Therefore he is able also to save them to the uttermost that come unto God by him, seeing he ever lives to make intercession for them.
Luke 11:13 If you then, being evil, know how to give good gifts unto your children: how much more shall your heavenly Father give the Holy Spirit to them that ask him?
Luke 15:17-18 And when he came to himself, he said, How many hired servants of my father's have bread enough and to spare, and I perish with hunger! I will arise and go to my father, and will say unto him, Father, I have sinned against heaven, and before you.
John 10:16 And other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd.
1 John 1:9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.

Salvation is never lost

Our righteousness is like filthy rags before God, who had compassion on us and sent his one only Son Jesus Christ for our sake to die upon the cross of Calvary for the remission of our sins, which Jesus bore upon himself so that any one seeking salvation through the blood of Jesus Christ after confessing his sins to him will be saved. It was not by works of righteousness that we have done but according to his mercy he saved us. He is the Savior who bore our sins and washed us in his precious blood. After that we are justified by his grace so that we should be made heirs according to the hope of ETERNAL LIFE.

Titus 3:5-7 Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost; Which he shed on us abundantly through Jesus Christ our Saviour; That being justified by his grace, we should be made heirs according to the hope of eternal life.

The God who gave his one and only son for our sake so that we are made heirs to the eternal life can not be unfaithful to us to take away the salvation offered to us once. Every person is prone to commit sins even after being saved but that does not disqualify to the eternal life. God will chasten us for the sins that we commit after having obtained salvation but will certainly not take away he gave to us as gift. The benevolent action on the part of giving abundant grace in not taking away the salvation once offered to us should not be misused by us, lest we would face severe chastisement even while we are on this earth. God will make us to realize that we have sinned even after being saved and by chastisement will bring us back to his feet. He, who has won us for himself as his children will not let us go in to the fold of Satan any more nor will allow us to end up in to the lake of fire. This is the blessed hope we have in him and that is true.

Saints in Old Testament period looked forward for Messiah who was to come just as was seen when a lamb was shown by God and that lamb was sacrificed in place of Isaac when Abraham obeyed God and was ready to offer Isaac. 

Isaiah 61:10 I will greatly rejoice in the LORD, my soul shall be joyful in my God; for he hath clothed me with the garments of salvation, he hath covered me with the robe of righteousness, as a bridegroom decketh himself with ornaments, and as a bride adorneth herself with her jewels.
Habakkuk 3:18 Yet I will rejoice in the LORD, I will joy in the God of my salvation.

Saints in New Testament period look back to the Messiah who was crucified for our sake and took upon himself our transgressions and by whose stripes we are healed. 1 Peter 2:24 Who his own self bare our sins in his own body on the tree, that we, being dead to sins, should live unto righteousness: by whose stripes ye were healed. Very important two verses from New Testament are as follows. These verses show that we the saved children of God will have everlasting life and have passed from death unto life.
John 3:15-16 That whosoever believeth in him should not perish, but have eternal life. For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. John 5:24 Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life. We are saved through the blood of Jesus Christ who is our Good Shepherd. He gave life for our sake so that we may not perish and added to that Jesus Christ himself said no one can pluck us out from the Father's hand. He also asserted that He and the Father are one. 
Salvation is not available through any other person or any other god under heaven nor is available through the good works. Any amount of good works done by us will not save a person. Salvation can not be purchased. Silver or Gold can not used for purchase salvation. Salvation is available free of cost exclusively for those who ask forgiveness of their sins and accept Jesus Christ as his/her personal Savior.

Few references which confirm that once saved always remain saved and
salvation is never lost are as follows:

Acts 4:12 Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved. - Salvation is through Lord Jesus Christ, who preserves his children from falling away. Once a person is saved, Jesus preserves him through the end of that person's earthly life.  Jesus brings him home by proper chastisement, but will never let him be lost for ever.
Romans 1:16 For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek. - Men should be ashamed of their sin but not of gospel of Christ because it is the power of God that saves him. After God exercising his efficacious mighty power to save a person, He will also take care to see that his child does not fall away totally, but will help him overcome obstacles.  God does not tempt any body; rather he provides way alongside, for his child to escape from the temptation brought in to the life of a child of God.  
Romans 3:23-24 For all have sinned, and come short of the glory of God; Being justified freely by his grace through the redemption that is in Christ Jesus:
Romans 6:6-7 Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin. For he that is dead is freed from sin.
Romans 10:9-10 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.
Ephesians 2:8-9 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: Not of works, lest any man should boast.
Ephesians 6:17 And take the helmet of salvation, and the sword of the Spirit, which is the word of God:
1 Thessalonians 5:9 For God hath not appointed us to wrath, but to obtain salvation by our Lord Jesus Christ,
Hebrews 2:3 How shall we escape, if we neglect so great salvation; which at the first began to be spoken by the Lord, and was confirmed unto us by them that heard him;
Hebrews 9:28 So Christ was once offered to bear the sins of many; and unto them that look for him shall he appear the second time without sin unto salvation.
1 Peter 1:5 Who are kept by the power of God through faith unto salvation ready to be revealed in the last time.
1 John 2:1 My little children, these things write I unto you, that ye sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous:
Revelation 7:10 And cried with a loud voice, saying, Salvation to our God which sitteth upon the throne, and unto the Lamb.
Revelation 19:1 And after these things I heard a great voice of much people in heaven, saying, Alleluia; Salvation, and glory, and honour, and power, unto the Lord our God:

Dear friend,

Though I was born again Christian and lived a good life for many years, yet there were times when I backslid. God does not tolerate backsliding. He wants backslider to come back to him. He warns, chastises, and makes his child to come back to him. God chastised me when I sinned, yet he did not leave me. Backsliding is like a disease, which attacks a person, when his immune system goes down. When a child of God neglects meditating on the Word of God, his dependence on God decreases and it is that time Satan takes advantage and attacks the weak child of God.

Jesus was nailed upon the cross of Calvary, shed his precious blood for your sake, just as he did for me, died for your sake on your behalf, was buried, and after providing purification for your sins, he ascended in to heaven and sat down at the right of the Majesty. He is loving God and He is living God.