My experience has been that those who have problems with the doctrine of eternal security have a distorted understanding of what took place at the Cross. That may sound as if I am being critical. But in reality I am more puzzled than anything else. When I think of Calvary, and the price that was paid to provide me with salvation, the thought of my having the power to undo all of that seems preposterous.
Especially considering that Jesus said that he would never leave us or forsake us, if we belong to him if he is our Good Shepherd.
He also said that he is the good shepherd and that he would leave the 99 to go find that one Lost Lamb.
Then you have the fact that he gave us eternal life. If we could somehow lose our eternal life that he died to give us, then it wasn't really eternal was it.
You have no power to undo what Christ did on the cross - none of us do. But God Himself has given each of us free will, so that we are free to accept what Christ did or reject it.
Hebrews 2:1-3 "For this reason we must pay much closer attention to what we have heard, so that we do not drift away from it. For if the word spoken through angels proved unalterable, and every transgression and disobedience received a just penalty, how shall we escape if we neglect so great a salvation?
Your false doctrine, eternal security, would have us believe that once we receive salvation, we automatically lose our free will - we no longer have the free will to reject Him - He is FORCING us to stay with Him. Your false doctrine makes God a tyrant.
According to your false doctrine, even if we apostatize and commit idolatry and gross sin, and deny Him, He will still force you to be in the body of Christ. But what does the scripture say?
2 Timothy 2:12 "If we deny Him, He also will deny us."
Hebrews 3:12-13 "Take care, brethren, that there not be in any one of you an evil, unbelieving heart that falls away from the living God ... so that none of you will be hardened by the deceitfulness of sin."
It's true, Jesus will never leave us or forsake us, but He will not stop us from leaving or forsaking Him.
Jesus is our Good Shepherd and He did find us, lost lambs. But once we're found, he doesn't lock us up, so we never stray again. No, He continues to give us the freedom to choose between right and wrong.
Then there's the age-old eternal security talking point: If we can lose our eternal life, then it wasn't eternal, was it? I answered that in #33.