Want to start an incendiary debate among a group of Christians? Ask them if they think it's possible to lose one's salvation!
The idea of there being a human factor in our salvation strikes some Christians as heretical and others as common sense. This particular "hot potato" tends to divide Christians into Calvinist and Arminian camps.
Calvinists (in general) strongly uphold God's sovereignty and emphasize the predestination of the elect. God's grace and election are paramount. Christians are eternally secure in their salvation. Nothing can separate them from the love of God in Christ.
Arminians, on the other hand, focus on the element of freedom that God has chosen to endow humanity with. Once people respond to God's grace in Christ, there is an expectation - but not a certainty - that they will keep walking in it.
Each side of this debate has its favorite scriptures. As an Arminian myself, Hebrews 6 is on my speed dial. The author of Hebrews writes: "For it is impossible to restore again to repentance those who have once been enlightened, and have tasted the heavenly gift, and have shared in the Holy Spirit, and have tasted the goodness of the Word of God and the powers of the age to come, and then have fallen away, since on their own they are crucifying again the Son of God and holding him up to contempt" (vs. 4-6). To me, this indicates that it is possible to exit a state of salvation - indeed, to do so is quite perilous to one's soul, for there is no way to return to it!
That is why I, personally, do not talk about "losing" one's salvation. If I were in danger of losing my salvation as I am my car keys or favorite hat, I would be overwrought with anxiety! Instead, I believe that what is possible is a kind of "throwing away" of our salvation, as in a disowning of our spiritual family and Father. It isn't something that is going to happen without any effort, perhaps strenuous spiritual effort - but it can be done.
At least, that's my opinion. What's yours?