This is less a case of "powerful enough" and more that Christianity upholds that God is changeable, and expects people to _act_ and not merely trust that he will do everything for him. (Certain prosperity sects excluded.)
There are several times when significant figures such as Moses, David, Jeremiah, and so on, negotiate a new outcome with their God. There are also other times that their God refuses to act, because the faithless have fallen away.
They "wandered around in the desert", a rather small patch of desert, mind you, because of a lack of faith. The 40-ish years in the desert, to age out those who failed in their duty, rather than to enter into their "Promised Land". Moses was also forbidden from entering Cana'an, because he tried to act on his own, instead of in tandem with his god.