Lauren shared several photos alongside her soon-to-be husband early Thursday morning ... all featuring Pope Francis in his full regalia, shaking hands with Sanchezos and posing for pics.

Both Sanchez and Bezos dressed in their Sunday best for the meeting, with their black outfits offsetting the Pope's perfectly.

These 2 hang with huge celebs on the reg -- like Orlando Bloom, Katy Perry and Leo Di Caprio -- but you can tell by their smiles ... an audience with His Holiness is next level. Even for them.

Lauren added a heartfelt caption to the post ... lauding the Pope for his humor and wisdom, saying he told them to keep lightness in their hearts, and not to take life too seriously.

That said, the 3 didn't sit around talking yacht trips and private jet rides ... instead, LS says they dove into the importance of climate action -- a passion she says the trio all share.

We knew Jeff and Lauren were in Rome -- we told you about their trip to the famed Trevi Fountain to toss coins and kiss. They added a romantic stroll and lavish dinner to their Roman holiday too ... but, clearly they were in town for more than sightseeing.

BTW ... the Pontiff is active on X -- but, he hasn't posted about sitting with the couple. So, no endorsement from God's mouthpiece quite yet.