Belief in God is rational.
Everything has a cause. So unless there is a first cause, then you would have an infinite regress. And then nothing could exist. Therefore there must be a first cause. Therefore God, the first cause, exists. QED. (You could prove the first step a priori that everything has a cause by noting that nothing can come from nothing. This makes it a priori, not just an empirical observation).
t60 D Minor This is an edited version with a final part in 6/8 time. The idea to end with 6/8 time is an idea of Mozart in one of his B flat symphonies or serenades. [I forget which.]