"Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort you that ye should earnestly contend for the faith which was once delivered unto all the saints." (Jude 3 KJV)
"Examine yourselves to see if your faith is genuine. Test yourselves. Surely you know that Jesus Christ is among you; if not, you have failed the test of genuine faith." (2 Corinthians 13:5 NLT)
What is this faith all about? And why the struggle? To try and make a point for what I truly believe, I will bring the humanistic view of birth into conversation; which basically tells us that we are only born once in this world, and then we are dead! If that doesn't compute or meet with your understanding of this life, then you don't know what the Bible says about the basic human life: "For you were made from dust, and to dust you will return." (Genisis 3:19b NLT)
With that, I will try very hard to make this very simple and easy to understand. When we have been born again, that new birth is not temporary, as the human life; the new life we were given is eternal and is once and for all time; infinitely! This is the foundation of the faith we have in accepting Jesus Christ into our hearts; that is because Christ Jesus in alive forever and ever, and when we were given new life in Christ, we too are alive forever and ever!
Whatever you might think of that, the main thing is whether or not your faith is genuine and you are sure about the new life that you have been given. I hate to say it, but that is where we have the struggles and the doubts! It really doesn't need to be that way; but from time to time, even the strongest saint will have some doubts, it is only because they are still human.
I am bringing this point up, only because Jude has made it apparent, saying, "which was once delivered to the saints." Looking up that word, "once," it basically means, "one time," and "once for all." In other words, the new life that we have been given in Christ has no end! This makes no sense to some; I am pretty sure of that! Be that as it may, those who might possibly lose the salvation they might have been given, if it is true salvation, it was secured by His grace and not human effort; therefore, human effort is not able lose what Christ has already done!
With out a doubt, I know for a fact that this that I just said will not be accepted by many; which is not really all that surprising. I have seen the hate in some who have witnessed the fall of someone that was once a great minister; it is hard to imagine what that might feel like, from whatever side you are on. But I truly believe that God's word is not void, just as He has said...
""Come to me with your ears wide open. Listen, and you will find life. I will make an everlasting covenant with you. I will give you all the unfailing love I promised to David. See how I used him to display my power among the peoples. I made him a leader among the nations."" (Isaiah 55:3-4 NLT)