Q: Can you use the Finger of God’s Ability to avoid actions such as Steal a Keeper?

A: No. The Finger of God reads, “Once, during your turn, you can smite (i.e. discard) any Creeper, then put this card back into your hand.”

So the Finger of God can only be used to Smite something during your turn, therefore you can’t Smite and tuck it back into your hand during someone else’s playing of Steal a Keeper during their turn.