Can you lose your salvation? This has been an issue of great debate among Christians. Let me organise my answer into a couple of points.
(1) The bible speaks of the eternal security we have when we become Christians. eg. Jesus says "no one is able to snatch them out of my father's hands." John 10:29. Paul writes, "whom he predestined, he called, whom he called, these he justified; and whom he justified, these he glorified." Rom 8:30.
(2) The bible also speaks of Christians falling away. Heb 6:6 talks about the falling away (apostasy) of those who were partakers of the Holy Spirit. Paul also writes, "Now the Spirit expressly says that in the latter times, some will depart from the faith, giving heed to deceiving spirits and doctrines of demons." 1 Tim 4:1
How do we reconcilse these?
(1) It is not possible to lose your salvation through normal sinning, ie. lack of good works. If you could lose your salvation through sinning then it is another way os saying that salvation is by works. Salvation is by faith and not by works so no man may boast. (Eph2:8) When a Christian persist in sinning and grieving the Spirit of God after he becomes a Christian, he does not lose his salvation. However three things happen:
(a) He loses the joy and experience of his salvation (Psalms 51:12) This means he loses his assurance of salvation. Sin acts as a wedge in our relationship with God and silences the voice of God in our lives. Our prayers become futile and the presence of God is withdrawn from our lives.
(b) He comes under the corrective discipline of God. Heb 12:6 says, "For whom the Lord loves he chastens, and scourges every son whom he recieves." God cannot be mocked. Time and time again we see God send the nation of Israel into captivity, oppression and drought to cause them to repent and turn back to Him. He never stopped loving them, never forsook them. If we have accepted HIm as Lord, and continue to sin, God will not let us go or leave us alone. Many Christians continue to suffer in this life not knowing that they have brought themselves under the discipline of God.
(c) He will be judged by Christ at the second coming. At the second coming, Christians will be judged according to how we have lived our lives(2 Cor 5:10). This is a separate judgment from non-Christians. The judgment here is not unto eternal life, but as to rewards or lost of them. 1 Cor 3:13-15 says on that day, "each one's work will become clear, for the Day will reveal it, because it will be revealed by fire and the fire will test each one's work, of what sort it is. If anyone's work which he has built on it endures, he will receive a reward. If anyone's work is burned, he will suffer loss, but he himself will be saved, yet so as through fire." To those who have lived in sin after conversion, there will only be regret and shame as we enter heaven and are disqualified from any rewards.
(2) The Christian may lose his salvation only if he abandons the faith (apostasy). Faith in, faith out. The bible calls this sin blasphemy against the Holy Spirit (Matt 12:31) Paul illustrates this in Heb 6:4-6,where he says "it is impossible for those who were once enlightened and have tasted the heavenly gift and have become partakers of the Holy Spirit, and have tasted the good word of God and the powers of the age to come, if they fall away, to renew themselves again to repentence." This condition is one where after having experienced the power of the Holy Spirit in our lives, in conviction and regeneration, to walk away from God. It requires a heart so hardened, so cold towards God that there is no more a possibility of guilt or remorse, to make repentence impossible. The examples of these prophesied in the bible are of deception by demons and false prophets in false religons .
(3) Conclusion. God will not let us go once we have accepted Him. Neither Satan not others can snatch us away from his hand, for we are being kept by the power of God through faith for salvation (1 Peter 1:5). But if we choose to deliberately abandon the faith and say to God, "I dont need you or your salvation or want you to be my God anymore", I suspect God will in His respect of our human free will, let us go. This is not something we may want to test Him on.