I have severe OCD so I'm unsure if my concern is valid. Years ago my non-practicing barber said he doesn't pray but he's still Muslim and my reply to his statement was "yea", basically affirming/agreeing to what he said, do I have to go and tell him that's not correct or leave it?

Ustadh AbdulAziz al-Haqqan

There is a difference regarding this matter but u can always advise him may Allah reward you.