Adhere: to stick to. 

This is the primary meaning.  For example: The stamp adheres to the envelope.  (If you are under 20 years of age, look it up.)

There are several other meanings for adhere. 

Adhere also means, to be joined.  Figuratively, the word means, to hold to.  People might adhere to a party, a leader, a church, or creed.

In all the examples, to adhere is to stick to something.  This is because the word comes from two Latin words.  Ad means to, or toward.  Haerere means, to stick.

These two words also give us the English, adhesive

I also found in interesting that the word hesitate comes from haerere.  Hesitating?  Perhaps you are stuck.

Perhaps this will help:

I am a true believer.  Ignore the three paragraphs directed at children and true believers.