Ask people to clarify what they no longer believe

We love to see God change people; by his word, because of his grace, thru his spirit, using weak and frail “us”. We rejoice in that change.

So help people to articulate their change. Ask them what’s gone on, what actually is different?
Ask them what they used to believe, and why they don’t believe it any more.

There’s more chance that the change will stick if they understand it better.