God = Godan = Wodan = Odin, so actually, as Lightning-Wings said, the term ‘God’ is a proper name for Satan, which the christians co-opted for their deity when they spread into the Germanic regions of Europe (the Germanic tribes were already using the term “God” for Odin). For this reason, the more ardent christians advocate against the usage of the term ‘God’ to refer to their diety as it is ‘pagan’ 🙵 ‘evil’. So if anything, you are actually doing well by sꜽing “Oh my God”.