What's the recipe for a perfect religion with strict and passionate devotees?

Most Muslims I know are all very devout and passionate about their religion. I really haven’t seen any other religion have such a large percentage of people willing to do anything to uphold their religious views. And something about Islam is attractive enough that it drives others to convert to it too. I have also seen this to a lesser degree with Judaism. My question is: what are the attributes of these religions that make people follow them so rigidly? For example: even the more laid back (or pretending to be laid back) Muslims refuse to bend on the core principles. I didn’t add Christianity to this list because I know many who are “Christian” but never go to Church, pray etc. So what gives religions like Islam and Judaism that holding/controlling power over it’s devotees?

Some things to remember: NO BASHING any religion at all. At all. I would like you to objectively analyze whatever religion the Q instead of answers like “that’s because Islam is the perfect religion and people who follow it go to heaven” etc.