Thom and Uthgar I think go back too far for him to just cut ties. Yeah, Erathis saved him, but as I'm going through the episodes again, Uthgar was always there as Thom's boy, and he even was converting the others
No one else has a God/dess before Erathis besides Thom with Uthgar. Junpei just had his Djinn, Tum only had his daggers and the Darkblades. Aludra had primal gods that were more just sorta there, and Harper is a Sorcerer, the only thing they worship is the magic in their veins and their past, with Harper's being especially dark.
But Thom has and always will have Uthgar, especially with the complicated past Thom has being a clone/not a clone/killing and remembering being killed by himself. Too much chaos for that to be convinced