War Machine Calls On ACLU For Help ... Let Me Break Bread!

War Machine's freedom of religion is under attack while he sits behind bars in Nevada ... so he claims, and the ex-MMA fighter is calling on the ACLU for help.

War -- who faces life in prison on charges of attempted murder after allegedly beating ex-GF Christy Mack -- claims Nevada's High Desert State Prison won't let him properly observe Passover.

War is on the prison's list of inmates who identify as Jewish. We're told he'll have access to a rabbi and special meals.

What he WON'T get is the right to attend Passover services because his prison status restricts his movement.

No word on whether the ACLU will champion his cause.