Yes, but the reason why people don't take Vader's devotion to the Force seriously is because they don't believe the Force exists and they think it's just superstitious nonsense. It's likely that after the end of the Jedi after a while people only remember the lightsabers. Palpatine might even have encouraged that: better to have extra tricks up his sleeve that people don't know (much) about.

Yoda is certainly religious, and in my estimation Qui-Gon as well. But Obi-Wan seemed less so, for example, and Anakin also doesn't seem like the religious type. The Jedi also don't seem to attempt to spread their religion beyond the members of the Jedi order.