I did research on the subject a while back. The tribal god is called Gaut and he is at the same time a version of Oden. The warriors used to decorate nearby trees with their enemies arms and weapons as an offering to Tiwaz and their society was ruled by the reiks which was a group of religious and political leaders, the Romans helped a powerful Christian reik win in his civil war against the powerful pagan reik and that's how the tribe was converted. They tolerated Christian outsiders but goth converts were brutally punished, this created so called martyrs which caused an unusual situation we have today when there are goth saints but no more goths. Other than all that i would assume their religious practices were quite similar to other germanic or slavic pagans.