Ye was all over D.C. Saturday with his fam, first stopping off at HBCU Howard University to do his traditional Sunday Service ... then heading over to George Washington University's Lisner Auditorium later in the day for a listening party -- much like in Detroit.

Check out this video TMZ obtained from inside the session ... Kanye was talking to the audience in between tracks -- which sound amazing, BTW -- and said it flat-out at one point ... he's a recent convert to Christianity. Ye got a round of applause for the news.

He also went on to invoke Jay-Z's name during his speech, saying that unlike a line that he attributed to Jay -- from his song "Can't Knock the Hustle" -- Ye isn't here for entertainment anymore ... he's just here to spread the Gospel. How 'bout that?!

He did exactly that too during the get-together -- preaching about what he used to value and hold dear compared to now, while also quoting A LOT of scripture along the way.

The signs have been there for a while now that Ye's fully embraced his faith -- he's been holding Sunday Services since January, and Kim just had the kids baptized in Armenia.

Oh, and if you're wondering what Kanye's gonna rap about from now on and what his music's gonna sound like -- at least for this round -- you get a snippet of that here too. Still no official word on when this thing's gonna drop -- but hopefully soon.