Yes I know, it's the ex graie deus that makes it sound like this (as if his wife isn't present and still near Berlin, but maybe, since there was not much consistency in the ways of writing, the Latin writing of the clercks wasn't always making sense as well ?
Maybe the ex graiedeus, was supposed to be ex grati deus, which translates as ''guidance from God'' or, depending on the context, it also translates as ''grateful to God'', which, if a healthy child was born and baptized, of course would make sense in a Church ...and by the Grace of God as Chantal already mentioned of course would make sense as well at a baptism...I think it is the inconsistency in writing those days, it now doesn't seem to make any sense...(and perhaps the clerck wasn't such a good Latin writer as well ?)