The short answer to this question is, no, a true Christian cannot “give back” salvation. Oddly enough, some who agree that a Christian cannot “lose” his salvation still believe that salvation can be “given back” to God. Some who hold this viewpoint will take Romans 8:38-39 and say that while nothing outside of us can separate us from the love of God, we ourselves can choose, in our free will, to separate ourselves from God. This is not only unbiblical; it defies all logic.
To understand why it is not possible for us to “give back” our salvation, three things are necessary to grasp: the nature of God, the nature of man, and the nature of salvation itself. God is, by nature, a Savior. Thirteen times in the Psalms alone God is referred to as the Savior of man. God alone is our Savior; no one else can save us and we cannot save ourselves. “I, even I, am the LORD, and apart from me there is no savior” (Isaiah 43:11). Nowhere in Scripture is God ever portrayed as a Savior who depends on those He saves to effect salvation. John 1:13 makes it clear that those who belong to God are not born again by their own will, but by God’s will. God saves by His will to save and His power to save. His will is never thwarted, and His power is unlimited (Daniel 4:35).
God’s plan of salvation was accomplished by Jesus Christ, God incarnate, who came to earth to “seek and save that which was lost” (Luke 19:10). Jesus made it clear that we did not choose Him, but that He chose us and appointed us to “go and bear fruit” (John 15:16). Salvation is a gift from God through faith in Christ, given to those whom He has, before the foundation of the world, foreordained to receive it and who have been sealed by the Holy Spirit into that salvation (Ephesians 1:11-14). This precludes the idea that man can, by his own will, thwart God’s plan to save him. God would not foreordain someone to receive the gift of salvation, only to have His plan destroyed by someone wanting to accept that gift and then return it. God’s sovereign omniscience and foreknowledge make such a scenario impossible.
Man is, by nature, a depraved being who does not seek God in any way. Until his heart is changed by the Spirit of God, he will not seek God, nor can he. God’s Word is incomprehensible to him. The unregenerate man is unrighteous, worthless, and deceitful. His mouth is full of bitterness and cursing, his heart is inclined toward bloodshed, he has no peace, and there is no “fear of God before his eyes” (Romans 3:10-18). Such a person is incapable of saving himself or even seeing his need for salvation. It is only after he has been made a new creation in Christ that his heart and mind are changed toward God. He now sees truth and understands spiritual things (1 Corinthians 2:14; 2 Corinthians 5:17).
A Christian is one who has been redeemed from sin and placed on the path to heaven. He is a new creation, and his heart has been turned toward God. His old nature is gone, passed away. His new nature would no more desire to give back his salvation and return to his old self, condemned to hell for eternity for sin, than a heart transplant recipient would want to give back his new heart and have his old, diseased one placed back in his chest. The concept of a Christian giving back his salvation is unscriptural and unthinkable.