Can I use the Finger of God on other players' turns?
Yes you can. The action clarifier makes sure the card is not overpowered--there have to be reprecussions. For the card "Excalibur," the reprecussion is that you can only play it on your turn. For "Finger of God," the reprecussion is that it goes back into your hand. Since you have to wait until your next turn to play it again, it is what keeps it in check.