ratiocinator
Lightly seared on the reality grill.
It makes sense that a God would be self existing, since God is the first cause. The law of cause and effect means that everything must be self existing. A singularity sounds like an aspect of nature it doesn't sound divine or supernatural. That's why God being the self existing first cause makes more sense.
Why does it make more sense? What does "divine or supernatural" mean other than giving you an excuse to say that it then doesn't need a cause?
Time and causality are internal to the universe (the space-time) why do you think that they would apply to the space-time as a whole? Recognising that simple fact actually does make more sense.