Saying "I believe in God but not religion" makes about as much sense as saying "I believe in Brahma, Vishnu, etc., but don't follow Hinduism"

Why do people think they could separate a very specifically defined deity from religion?
If you say you believed in "God" you're referring to the Abrahamic god who is the deity of Judaism, Christianity, Islam, the Baha'i faith and related sects, meaning you'd HAVE to follow one of those religions. If you don't, stop using that misnomer.