believing is like 'faithing'

There are some technical theological terms for the difference between what we believe and the act of believing.......they are in Latin of course.......but let us not confuse the two.

Believing is a verb that depicts an action - active faith in another.  It is not a doctrinal test. 

Instead, belief is "more like a marriage vow - 'I do' as a pledge of faithfulness and loving service to and with the other"* - in this case our Lord Jesus and the Creator God.  Hebrews 11.1 says it nicely.

When we go out and serve our neighbor it reflects our trust in the promises made in and through Jesus: his work, his gifts, his forgiveness, his resurrection.  We can talk about doctrinal stuff later.  For now, trust.

* Diana Butler Bass gives us this description in her book Christianity after Religion, p 117.