The singer and his model wife attempted to keep a low profile as they exited the Churchome Church in Bev Hills on Wednesday evening. The lovebirds -- who got hitched in 2018 after a whirlwind engagement -- looked subdued as they made their way from the religious service.

We'll be honest, Justin looks a little down and out here ... wearing a dark oversized sweatshirt and a matching scarf that covered his face. Hailey was rocking a cheery yellow and gray sweater ... but she appeared equally somber.

They made a quick getaway in their $90,000 Tesla Cybertruck -- refusing to comment on nosy paps who were asking pretty wild questions about their marriage.

The backdrop to this moody outing is actually Hailey's dad Stephen -- AKA Alec Baldwin's brother -- sparking some concern among their fans when he reposted a plea for prayers for his daughter and son-in-law.

Overlaying a video of Justin singing, a message read ... "Christians, please when you think of Justin & Hailey, take a moment to offer a little prayer for them to have wisdom, protection and to draw close to the Lord." Stephen didn't post this originally, but he did repost it.

Of course, Faith is a major part of Justin and Hailey's relationship ... and ditto for Stephen obviously. Unclear why Stephen might've been asking for prayers ... but it worried some.

Justin and Hailey definitely hit the town a lot -- but they don't really talk much, especially Justin these days ... who's really stepped away from the spotlight and performing amid health issues. They've also been open and honest about struggles in their marriage early on.

Looks like the two of them are once again seeking out spiritual guidance ... and Papa Bear wants to send them some love.