The reason why Calvinism and Arminian theology exist is because there are texts that seem to support both. The real issue, however, is which texts are controlling. In other words, if Text X is meant to be the overarching truth by which Text Y must be interpreted, or if Text Y is the overarching truth that must interpret Text X. So, for instance, when we speak of Jesus as the God-man, are those texts that talk about Christ as a human the overarching truth that must then inform our understanding of the verses that speak of Him as God, and therefore, Christ is just a human who perfectly reflects God, or is it the other way around, and Christ is God who has become a man as well? Do we read James in light of Paul (a faith that produces works saves), or Paul in light of James (works need faith to be saving)? As you can see, what one decides about controlling passages is no small factor in whether one will end up trusting in orthodox Christianity (a cedar of Lebanon) or one who believes in heterodoxy, or worse, heresy, a broken reed.
So this brings us to the question of whether one can lose his or her salvation. I'll simply ask the question and then answer it. Can someone lose his salvation? The answer: Yes and No.
Now, you may be saying to yourself, "That makes no sense. Those are contradictory." Well, actually they aren't if you understand that Scripture speaks from two perspectives: God's and man's. In fact, as I've mentioned before the Bible starts out doing this in Genesis and continues throughout to speak in this way. So from man's perspective, evil reigns and God many times loses His fight with it. From God's perspective, evil is no threat at all, has been completely subdued, and remains under His sovereign control.
Likewise, from man's perspective, people lose their salvation all the time. That's our experience. Someone believed strongly and now doesn't believe anymore (or much less than he did before at least). But from God's perspective, no one ever loses his salvation, since God elects His own from the beginning and completes the work He started in them until He raises them up on the last day.
So, yes, we can lose our salvation from our perspective. No, we cannot lose our salvation if we view it from God's perspective, since Christ loses none of the number that the Father gives to Him.
But what happens when we seek to use one of these as a control of the other, and get it wrong? If God's perspective is not simply a perspective, but the eternal truth of the matter, then that means that interpreting passages that deal with our losing our salvation as absolute is to misunderstand the perspective at which one is looking.
I can have the perspective that Joseph did when his brothers sold him into slavery and ended up in prison, and then say, God has been overcome by evil. He has lost His bout with it. But that's the perspective from prison. The true perspective is one that sees both means and ends, not just the means as ends. In other words, we can get caught up in our experience and think that we are declaring an absolute rather than what it just looks like from our perspective; but by doing so, we end up missing the truth of the matter: that God is merely purposing the evil of Joseph's situation for the good and salvation of many. The same can be said from our perspective of the cross, if we do not consider the resurrection and exaltation of Christ and our salvation to follow.
My point simply is this: the perspective of God, throughout Scripture, takes upon itself the controlling right by virtue of its nature. God's perspective is the eternal one. It's the one not bound by the limitations of human experience and thoughtfulness. Hence, it is not merely a perspective but what is true in the absolute sense. But man's perspective is just that, a perspective, and it merely looks at the means, as the means is what make up the total experience of the human observer. We don't live in eternity. We don't experience the big picture. We just see through our experience, and in our experience, evil wins, people lose their salvation.
But this is precisely why it is so dangerous to look at the means as the ends and construct one's theology based upon that perspective. That perspective isn't really true in the absolute. It's just true in our experience. It's a way to describe what happens in terms of what we observe from our perspective. It has nothing to do with what is really happening in the big picture of things, because in the big picture, evil doesn't win and no one loses his salvation.
Do we experience people believing and then rejecting the faith? Yes. Do people then lose their salvation from our perspective? Yes. Does anyone who is truly regenerated by God and has saving faith ever lose his faith and salvation? No, but that's something we get from the divine revelation of God's perspective. It's something we take on faith, because it is beyond our purview. But because it is the "view from above," that perspective needs to control our perspective. The finite and temporary means needs to be interpreted by the infinite and eternal ends, not vice versa.
So why am I saved? My perspective: Because I believed. Why am I saved? God's perspective: Because He chose me before the foundation of the world to believe. Why is another not saved? My perspective: Because he didn't believe. God's perspective: Because God chose to let him remain in his rebellion. Can someone lose his salvation? My perspective: Yes, people believe and then reject Christ all the time. God's perspective: No, He holds His chosen in His hand and no one takes them out of His hand.
Hence, when we read Scripture, we need to understand from what perspective an individual passage is speaking, because Scripture speaks with both voices, using language from both perspectives, and it assumes that we will understand that the divine perspective is controlling, even though it is completely fine with speaking from the human perspective in light of that divine perspective. The problem is when we exclude one from the other, giving us an imbalanced and distorted theology or practice, or we use the wrong perspective (i.e., the human perspective) as controlling and the interpretive guide for those other passages that give us the big picture perspective (i.e., God's view of all things).
So, Yes, you can lose your salvation, and because of that, you need to be encouraged to remain in the faith, and warned to hold fast to it with everything you've got. No, you can't lose your salvation at all, because God is its author and the one who completes it, and no one, not even our own tendencies toward faithlessness prevails against Him. He will complete His work to the very day of Christ. Hence, our perspective must be seen as the means (holding onto the faith, being sobered by means of being warned as though we can lose it so that we keep it), and God's perspective must be the overarching truth that interprets our perspective.
This does not discount either teaching, then, but puts one into perspective of the other. It tells us that we must, in our experience, take seriously the warning that it could be that we reject the faith and thus prove that the means of our faith to bring about the ends in our salvation has been lost. It also tells us that we should understand that no one who keeps that faith (i.e., has true faith that saves) had the possibility of being lost in the first place. But we don't know who we are: true believers who are elected or temporary believers who are not, and what we do in terms of believing (the means/our perspective) dictates the ends (again, from our perspective). But can we then attribute the security of our salvation to ourselves? No, because we have the truth of the big picture given to us by relating God's wholistic sight of things: Anyone who is saved is saved because he or she was elected before the foundation of the world to be saved, he or she will therefore believe to the end, and God will raise them up on the last day. Hence, our abiding faith is solely due to God's work in us from that larger view of things, and we cannot therefore claim the credit it looks like we can claim if we were to only take our perspective into account or use it as the controlling idea when encountering the divine perspective.
With this in mind, I'd like to look at the warning passages in Hebrews tomorrow.
So then, my beloved, just as you have always obeyed, not as in my presence only, but now much more in my absence, work out your salvation with fear and trembling ; for it is God who is at work in you, both to will and to work for [His] good pleasure. (Phil 2:12-13)