David Letterman Is Team Taylor Swift, Defends Her From NFL Haters

David Letterman is telling Taylor Swift's NFL haters to "shut up" about her romance with Travis Kelce -- even though he seems a little confused about who her boyfriend is.

The talk show host offered up a passionate defense of Taylor in a new clip he posted to his social media ... and yes, it's a fierce cosign of all things Taylor, whom he calls a bright light in a world full of darkness.

Also ... DL hilariously confused TK for Kelsey Grammer -- something he continued to mistakenly say, even after being corrected a couple times. Point being ... he loves Taylor!

According to David, Tay doesn't deserve any hate whatsoever ... especially if her stadium-packing credentials are anything to go by -- but to those who couldn't care less about her pop culture icon status and don't want her anywhere near the pitch ... he tells 'em to zip it.

David says T&T's PDA-packed relationship is a lovely, positive, and good thing for both the NFL camp and Taylor's own. He just wants more unity in the world, not division -- and he seems to think Tay-Tay provides that.

ICYMI, Taylor's been coming out to cheer on the KC Chiefs tight end since September ... though she's been heavily criticized for distracting from the sport by fuming diehard fans.

In fact, Tony Dungy even recently compared her to outside noise affecting the game itself in a Fox News interview -- and who can forget Taylor's viral stare-down with Golden Globes host Jo Koy when he mocked her NFL appearances during his opening monologue?

Clearly, the whole thing's a very divisive matter, but David's saying just let them love and live -- adding: "God, bless Taylor Swift and Kelsey Grammar (Travis Kelce)."