My aim is for this to be a kind of brief summary post, listing the various reasons I do not believe that true, authentic believers who have been forgiven, justified and saved can ever fall way into destruction and be lost. And therefore, anyone who fails to endure and persevere--in faith--throughout the race which is set before us demonstrates by their falling away that they never were savingly called by God.
1.) I John 2:19 "They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us."
2.) Matthew 7:21-23, where those who show up on the last day and say "Lord, Lord" (that is, they are professing Christians and not atheists or Muslims, etc.) and are rejected and condemned because they did not do the will of the Father, are told by Jesus that "I never knew you." Not just now, not just at a certain point when you fell away or lost your faith, but I NEVER knew you as my own.
3.) The Parable of the Sower (Matthew 13:1-23; Mark 4:1-20; Luke 8:4-15). Read together in all three gospels in which it appears, this parable makes it clear that true faith which receives the word in a good heart both bears fruit and perseveres, while those who fall away either did not understand or had no root in themselves. While not explicit, the impression given is surely no that the other three soils got off to a good start and were genuine, but only later problems arose. Instead, from the very beginning the word did not take root to grow.
4.) The Parable of the Weeds (Matthew 13:24-30). Here those who confess Jesus with their lips and who claim to belong to Him are--as so often in Jesus' parables--divided up into two groups, the wheat and the weeds or tares. Explicitly, the weeds in the field (i.e. professing believers who are not genuine and who will not be saved on the last day) are said to be planted by the "enemy" (Satan), and not by the good sower. However, on the last day (see Matthew 7, Matthew 25, etc.) these two groups--which are so often difficult or even impossible to distinguish now--will be separated before the judgment seat of God. However, there is no hint here that those who will be shown to be weeds on the last day started off as wheat or changed their course or identity halfway through. The opposite, in fact, is the case: they were planted as weeds from the beginning. Moreover, it is also significant that Matthew places this parable immediately after the parable of the sower, thus showing that the three "bad" soils that hear the word but fall away were never, indeed, "good" soils but instead never belonged to Jesus.
5.) The Promises of God: Passages such as Philippians 1:6; Romans 5:1-11; Romans 8:28-39; John 6:37-40, 44, 54; 10:27-30; I Thessalonians 5:24; II Timothy 4:18; Hebrews 10:39, etc. Simply put, these passages just cannot be understood within any framework that teaches that true believers who belong to God can fall away and perish. Thus, if Hymenaeus or Alexander or Demas or Judas were genuine believers who later fell away and forfeited their salvation, these promises cannot be trusted. We will always inevitably add the totally unwarranted "if" to them like John Wesley (See TRSBU, p. 22, also footnote 6)
6.) All true believers have the Spirit (Romans 8:9, etc.). And the Spirit is the downpayment and guarantee of our future inheritance, which is being kept for us and cannot be lost (see II Corinthians 1:22, 5:5, Ephesians 1:13-14, I Peter 1:3-5). God's preservation of them through faith will uphold them through all trials and keep them from stumbling.
7.) There are no "drop outs" in between the "already" and "not yet". Many passages teach this, such as Romans 5:9-10, Romans 8:28, Ephesians 2:4-8, Philippians 1:6, etc. Yet this is exactly what the loss of salvation view must hold to--that there really are people who experience the "already" of being forgiven, justified, saved, adopted, brought from death to life, and somehow become unforgiven, unjustified, unsaved, unadopted, and who regress back from life into death again. Yet there clearly are no passages in the NT which ever teach or even come close to inferring such a thing. Instead, present possession of the "already" of salvation always acts as a guarantee of future participation in the "not yet." We who have now received the Spirit of adoption (Romans 8:15) are waiting eagerly and confidently for our (future) adoption as sons (Romans 8:23).
8.) Denies the Assurance of Salvation: Of course, we have yet to discuss this topic and we are coming to it soon. But regardless of the difficulties that surround the doctrine of assurance, it seems radically clear that the NT writers not only think that it is possible for believers to have assurance of salvation, but even expect them to pursue it and experience it. I am writing these things that you might know that you have eternal life. However, if a true believer can lose their salvation by an act of their own will, then for all practical purposes there is no way I can ever really have any kind of assurance at all. For my will triumphs over God's grasp of me. My hold of Him takes priority over His hold on me. And therefore, I can only trust His promises as far as I can trust my own willpower and endurance. Which is not very far when life becomes hard and the power and desire of sin rears its ugly head. It is not a coincidence that the doctrine of assurance has never been a firm reality in Arminian theology.
9.) The Case of Judas' Apostasy: We saw last night the vast differences between Peter and Judas. Though both commit similar acts of treason and betrayal, and deny their Lord, Peter repents and is restored and Judas is not. We are given several insights into this in the NT. First, though Satan has asked permission to sift (plural!) YOU like wheat--the disciples, at least Peter and Judas--Jesus has prayed for (singular!) YOU, Peter, and when (not if) you get back up and start running again, turn and strengthen your brothers. Thus the intercession of Jesus is the difference between Peter and Judas. Second, the gospels make it clear all over (for instance, John 6:70-71) that Jesus knew from the beginning that Judas did not belong to him, but that Peter is in another class. Lastly, John 17:6-12 is crystal clear: "I have manifested your name to the people whom you gave me out of the world. Yours they were, and you gave them to me, and they have kept your word. Now they know that everything that you have given me is from you. For I have given them the words that you gave me, and they have received them and have come to know in truth that I came from you; and they have believed that you sent me. I am praying for them. I am not praying for the world but for those whom you have given me, for they are yours. All mine are yours, and yours are mine, and I am glorified in them. And I am no longer in the world, but they are in the world, and I am coming to you. Holy Father, keep them in your name, which you have given me, that they may be one, even as we are one. While I was with them, I kept them in your name, which you have given me. I have guarded them, and not one of them has been lost except the son of destruction, that the Scripture might be fulfilled."