Commandments are unlocked after you have researched the Commandments Card which allows Followers to learn from you as a God.

Examples of this are if you preserve trees they will consider them sacred, if you destroy rocks they will believe they are sinful. And also if you make them live near the shore they will believe this is were they should live though.

As of the v1.3.1 patch Followers didn't really do anything with these Commandments despite what they believed however v1.4 is suppose to give the followers the ability to learn and so this should change.