It makes a lot of sense ... Kanye's Sunday Service -- where he performs gospel and his own hits with a live band and choir -- has become a massive success, and his Coachella performance was one for the ages. And what do they sing at church services ... psalms!

Kim tweeted a text exchange from Kanye which read, "Beautiful Mother's Day. With the arrival of our fourth child. We are blessed beyond measure."

As for Mother's Day ... Kanye played a special Sunday Service show which included his and Kim's kids along with other members of the family and the children of family friends.

Kim says Psalm looks like Chicago's twin brother. He joins older sister North and big bro Saint as the sixth member of Kim and Kanye's growing family.

As you know ... KK and KW welcomed their new kid into the world last week, and he weighed in at 6 lb and 9 oz.

As we first told you... Kim and Kanye hired a new surrogate to carry their 4th kid to term -- but not because they were unhappy with the last one -- she was simply unavailable this time. The woman, who was in her early 20s, had a kid of her own back in December ... less than a year after popping out baby Chicago. So, the couple had to find another surrogate, whose profile still remains a mystery.

The surrogate went into labor while Kourtney and Kris Jenner were taping an episode of 'Ellen' with all the Kardashian kids. Kim was supposed to be there, but she obviously skipped the taping to attend a more pressing matter. It's pretty crazy, even Kris didn't know she was about to have another grandchild!!!

Kim's got a ton on her plate with the newest addition. She's actively studying to become a lawyer and recently helped with the release of 17 prisoners in the last 90 days. Not to mention she's a social media mogul, runs a cosmetics line and stars on "Keeping Up with The Kardashians."

Kim and Kanye used a leftover embryo they created to bring Psalm into the world.

Welcome to the fam, kiddo!!!