"I cum Deo" is the literal translation of "go with god" but I think that go with god is a modern phrase. Dominus Vobiscum is "the lord be with you" would probably be closer to what the intent of go with god is now in the early church.
Dominus vobiscum may be correct when addressing a congregation in church, as it is second person plural. Dominus tecum might be more appropriate in this case, from what I understand (second person singular).
I know that "goddess" in Latin is "dea, -ae", and that "immortal gods!" in Latin is "di immortales!", and "household gods" in Latin is "penates, penatium". Sorry that I don't know the translation for "god".