I believe in the eternal security of the born again believer, but that requires that they stay a believer. I agree that nothing can snatch a believer from the hand of God but that does not stop someone from walking away from Him.
I have worked with two minister that latter walked away because of faith challenges.
Read the story of this man
Charles Bradley Templeton[2][3] (October 7, 1915 – June 7, 2001) was a Canadian media figure and a former Christian
evangelist. Known in the 1940s and 1950s as a leading evangelist, he became an agnostic and later embraced atheism after struggling with doubt.
I just came across this while doing a search.
1Ch 28:9 "As for you, my son Solomon, know the God of your father, and serve Him with a loyal heart and with a willing mind;
for the LORD searches all hearts and understands all the intent of the thoughts. If you seek Him, He will be found by you; but if you forsake Him, He will cast you off forever.