But you would have to agree, their spiritual practice does not depend on the idea of a diety. Likewise for Taoists and Jains. Buddhism is pragmatic, and opposition to dieties would have brought about a backlash against them. Instead they absorbed the previous religious practices of a particular area, although these hybrid forms are mostly intended for the lay masses. Strictly speaking, one only has to follow the precepts and meditate. For me, rejecting God brought about the freedom of thought that made further development possible.