When we pressed, asking what he envisions for himself as his next big challenge ... Kanye didn't hesitate and told us straight-up -- he wants to turn his attention to prison reform.

Ye gets pretty detailed about possible solutions that he thinks would have an immediate impact in helping poor folks -- who are often minorities -- stay out of jail unnecessarily.

We also asked if he was considering getting Joel on his next album. Watch ... doesn't sound like JO wants to hop on the mic, but Ye's not opposed to the idea.

10:23 AM PT -- Kanye West and Joel Osteen had quite the chat Sunday at the Lakewood Church in Houston -- and one of the big takeaways was Ye going to bat for Joel and his reputation in the Christian community.

The rapper-producer noted that Joel was responsible for converting thousands upon thousands of people to the right path of Christianity, and for that alone ... Ye said the guy should be more praised than criticized for everything he does in God's name.

They talked about a lot more too -- Ye touched on his upbringing in the church, explaining that he found going to Sunday service as a kid was pretty boring ... even though his parents were staunch believers, bringing the family to a megachurch in Chicago 3 times a week.

He also discussed his 2016 mental breakdown, and how after that ... he felt he needed to move away from most of the people in his inner circle because they weren't real Christians, and were simply yes men who were beholden to the almighty dollar.

Speaking of that, Kanye also pumped himself up a bit by saying that he was the greatest artist that God ever created ... and now, he was working for the man upstairs again -- instead of working for the devil, which he believes most of his contemporaries are doing now.

There was a lot more, but all in all ... it was a pretty moving interaction Ye and Joel shared onstage, with Ye coming across clearly and even ending on an uplifting prayer.