Kurt Warner -- Tim Tebow Should FORGET the NFL ... For Now

Kurt Warner says Tim Tebow's best shot for an NFL career ... is to LEAVE the league -- at least for a while.

The former Super Bowl MVP was at LAX ... and he told TMZ Sports he doesn't believe Tim can secure another NFL job unless he plays in ANOTHER league first.

Kurt -- who knows a thing or two about roundabout paths to becoming a starting QB -- says he's rooting for the guy, but unless Tim makes the jump to the CFL or another pro league to hone his skills, his NFL career is done.