Something that sometimes works for me: When speaking, take a pause before the word you know you'll stutter on...in this case, "religion". After the pause, take a deep breath, and then say the word but add an "H" sound on it, and at the same time give a deep exhalation from your mouth. It will come out sounding like "hree-ligion". Might sound a bit awkward at first, but if you take the time to make it flow with the rest of the sentence no one should really notice anything weird.