Germanic is a linguistic category before it is anything else. Donald Ringe's reconstruction traces the descent from Proto-Indo-European to Proto-Germanic and then to the attested branches, and the peoples the atlas files under this heading, Goths, Vandals, Franks, Saxons, Lombards, Angles, Frisians and the Scandinavians, are grouped by that descent rather than by any shared polity or any shared cult.
The religious inheritance shows the same pattern of relation without unity. A common stock lies behind Old Norse Odin, Old English Woden and Old High German Wodan, and behind Thor, Thunor and Donar, but the traditions had already diverged for centuries before any of them was written down. Philip Shaw's work on Eostre and the matron cults shows how much of what survives is local, is female, and does not fit the Norse pattern that later readers project backwards onto it.
Conversion came piecemeal across roughly seven centuries, from the Gothic mission of Ulfilas in the fourth century to the Scandinavian kingdoms in the tenth and eleventh, and its manner ranged from persuasion to conquest. Because the Norse were converted last and wrote most, Norse mythology has come to stand for the whole of Germanic religion. It is the best documented branch, not the parent of the others.