No. Disbelieving when there is no evidence at all for a claim, is a rational sceptical view. There is nothing dogmatic about it. The onus for evidence is on those who are making fantastical claims for the existence of something, whether it is mystical super beings, aliens making crop circles, perpetual motion devices or magic wavy sticks that supposedly sniff out bombs.
Being agnostic makes no assumptions about god/gods - it just says that there is no evidence either for or against that isn't completely subjective.
Dogmatic beliefs either for or against are just that - beliefs - neither side can provide any evidence.