“Doubt isn't the opposite of faith; it is an element of faith.”

Should there be doubt in commitment, a wavering resolve, then that faith is weak. One may doubt themselves in personal perplexity but never the Creator or His calling. 

Here making a difference between faith and belief, I can't imagine an amalgamating compound of doubt and faith but, with doubt and belief, a composite hypothesis can exist as a chimerical gesture.

Faith is believing in something where there is no evidence.