Once Saved Always Saved?

       There is a large group of people in Christendom today who follow the belief that once you have been saved, no matter what you do in the future, there is nothing you can do to fall out of favor with God. In short, once saved, always saved. This is a concept that is nothing new, and one that John Calvin and his followers faithfully believed. But when one thinks on this logically, it really doesn't make any sense. Do we really think that after we have been saved, we can do whatever we want without repercussions? What if we converted to Islam, or became Agnostic? Would God still be happy with that decision? Let's look at this in another way besides logic, let's see as we always should do, what the Lord says about this important topic.
       Calvinism, to be fair, doesn't actually say you can do whatever you wish, but they say basically that the Holy Spirit will force you to obey and stay faithful. John Calvin wrote this, "They, whom God hath accepted in His beloved, effectually called and sanctified by His spirit, can neither totally or finally, fall away from the state of grace: but shall certainly persevere therein to the end, and be eternally saved." So, God will not allow one to fall away and be eternally lost, at least according to John Calvin. Is this in agreement with the scriptures, or is this simply a doctrine of man? Calvinists like to use 1 John 3:9 which they say means the child of God cannot fall from grace because he cannot commit sin. Part of the reason for this is because the KJV wrongly used the word commit here. According to Vine's Expository, the correct translation should be "doeth" as the RSV and ASV uses. In this sense, what the Bible is saying is that if you are walking with God, you can do no sin. If you sin, you are not with God!
       This thought continues with Paul in his letter to the Romans in chapter 6:1-2. "What shall we say then? Shall we continue in sin so that grace may abound? God forbid. We who died to sin, how shall we any longer live therein?" And in Hebrews 10:26 the author (most likely Paul) says if we sin after we have received the knowledge, there is no more sacrifice of sin, but we must repent of those sins. Why would Paul bother to tell us what we must do after we have been saved, if we can't sin after we've been saved? It seems there is a contradiction between Calvin and the Apostle Paul! John, one of the 'Sons of Thunder' writes in 2 John 9 "Whosoever goeth onward and abideth not in the teaching of Christ, hath not God". This is important, for he states 'onward', meaning from baptism. Again, why would John need to state that anyone who falls away after being saved, falls away from God if he is automatically saved? When we depart from the Word we no longer abide in Him, there is no preservative.
       Other verses that we can see the truth are as follows: Eph. 4:30 says we are sealed by the Spirit unto redemption only as long as we do not grieve Him. Jude 24-25 says God is able to keep us from falling but we must allow Him to lift us up. It isn't a question of God's ability but of our willingness to allow Him to do so. No one can separate us from Christ, not even Satan, if we don't allow it to happen. 1 Cor. 10-12 and James 4:10 says God provides a means of escape if we are willing to walk after Him. What more evidence do we need?
       Just in case you still aren't sure there is enough evidence, let's see what the Bible says about someone falling from grace. Gal. 5:4 says "Ye are severed from Christ, ye who would be justified by the law; ye are fallen away from grace." Paul again is showing there were some who had fallen away from Christ. The Apostle Peter also tells us that if we return to sin AFTER having obeyed the truth, we will fall from grace. There are many more verses that support this, but let's look at two examples in the Bible of this happening.
       The first one would have to be one of the closest men to Jesus. That of course would be Judas. Now some like to argue that Judas never was faithful to Christ, but by reading the scriptures, that would be a complete assumption. Nowhere does it say that Judas was a spy, or always knew he would betray Christ, but leans more to temptation and a moment of weakness and love of money. We must also not forget about the angels, who were created by God, yet some of them fell as well (Jude 5-6 and 2 Pet. 2:4). In short, our name can be removed from the book of life (Rev. 20:14-15). If it is, we will be eternally lost. The proof is right there before us, it is just a matter of whether we want to believe God, or the doctrines of men.