Fanatical

They are fanatical in their beliefs.

She was very fanatical about religion.

Tom is fanatical.

Layla was fanatical about the Spice Girls.

If you tolerate everything to the point where you lose yourself, you become either wiser or more fanatical.

Tom doesn't seem to be as fanatical as Mary seems to be.

Tom is a fanatical nationalist.

He's fanatical.

That team's supporters are really fanatical.

That team's fans are very fanatical.

fanatical devotion

fanatical belief

fanatical follower

The group was known for its fanatical devotion to its leader.

He’s a fanatical supporter of the local football team.