The explanation requiring the fewest assumptions is most likely to be correct.

Entia non sunt multiplicanda praeter necessitatem

Entities should not be posited unnecessarily.

Entities are not to be multiplied beyond necessity.

Never increase, beyond what is necessary, the number of entities required to explain anything.

God's existence cannot be deduced by reason alone.

Pluralitas non est ponenda sine necessitate. A plurality (of reasons) should not be posited without necessity.