In debate about the existence of god, theists usually present arguments which attempt to show that we are justified in believing that a god exists. This justification is epistemic: a belief is justified if and only if there are good reasons for thinking that it is true. Good reasons include a priori proof and scientific observations.
If that fails, they may present (‘prudential’) arguments which attempt to show that belief in god is justified even if we don’t know that such a god exists. This justification is consequential: a belief is justified if you benefit from holding the belief. There are several types of prudential arguments:
Even though the existence of God cannot be determined through reason, a person should wager as though God exists, because living life accordingly has everything to gain, and nothing to lose.
The Will to Believe
In general we ought to believe propositions if and only if we have adequate evidence in favor of them. Sometimes, however, the evidence does not allow us to come to a conclusion either way about the truth of a proposition. The question of the existence of god is not intellectually resolvable. Therefore, it is intellectually permissible to believe that a god exists.
Argument from Solace
Belief in God gives my life meaning and provides solace in times of distress. Without such a belief, I would be unable to cope with the traumas of daily life and my life as a whole would be immeasurably worse. So, I am (consequentially) justified in holding the belief and resisting any attempts to persuade me out of it.