Tim Tebow is definitely down with Jesus ... but he ain't down with "MY Jesus" t-shirts -- and he's threatening legal action because he says a website is illegally using his name to sell the merchandise.
TMZ obtained the cease and desist letter Tebow's attorneys sent to cubbytees.com last month -- in which they claim "The Merchandise makes it appear as if Mr. Tebow actually endorses Cubby Tees and its products."
Interestingly, the tee shirts in question do not use Tebow's image or name -- but instead spell out "MY Jesus" using the colors and font of his new team ... the NY Jets. In fact, the website clearly states, "This fun design is not officially endorsed by New York's backup quarterback or the Son of God, but plays off the themes of Tebow's faith and his new team."
Still, Tebow's attorneys are demanding the site stop "any use of Mr. Tebow's name and/or likeness" -- and according to Cubby Tees, Tebow already successfully petitioned eBay to remove the tees.
The shirt makers tell TMZ they aren't backing down, and actually sent a response to team Tebow ... saying the design "shares nothing with Mr. Tebow except for promotion of a common Lord and Savior." The shirts are still for sale.