"Can you lose your salvation?" This question was asked in a Men's Group I had attended at one time. I immediately said no. Then I was asked why I believed that. My answer was because the bible says so. It says nothing can..., at this point I was interrupted and Romans 8:38-39 was quoted: "...neither death, nor life, nor angels, nor principalities, nor powers, nor things present, nor things to come, Nor height, nor depth, nor any other creature, shall be able to separate us from the love of God..." and then came the explanation that we could not separated from "God's Love." Implying that God always loves us but that doesn't mean we are saved. However the verse that was in my mind actually was John 10:28 "And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand." I just didn't know where it was at the time. I believe both of these scriptures go hand in hand. Nothing can separate us from God's love nor pluck us from God's hand. Also Paul tells us in Romans 11:29 that God's gifts are irrevocable and salvation is, a gift from God.
The real dilemma here is that if we can be saved and then become un-saved. How then can you be saved again? According to Hebrews 6:4-6 "For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost, And have tasted the good word of God, and the powers of the world to come, If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame." So is it possible then for a saved person to willfully reject Jesus and the Holy Spirit? If so, and according to the verses above, there would be no hope of being saved again. This would be rejecting ones salvation, which is not the same as losing it due to sin.
We as humans still sin and sin affects our fellowship with God but not our promise of salvation. So therefore we repent of our sin to restore our relationship with God, not our salvation.
David wrote, after his great sin with Bathsheba and unto Uriah the Hittite, Psalms 51:12 " Restore unto me the joy of thy salvation; and uphold me with thy free spirit." Notice he said; Restore unto me the joy of thy salvation and not his salvation. Davids faith and trust in God kept him saved but his sin damaged his relationship with God. But then he repented of his sin and restored their relationship.