How can I be sure this will happen? - Luke 1:18
Faith is based on the fact that God keeps his promises - especially the promises that seem impossible
God had not forgetten Zechariah's prayers
He send Gabriel to tell to tell them they would have a son and their son would be the appointed to introduce the Messiah
Instead of thanking Gabriel, Zechariah spoke words of unbelief - Luke 1:18
God wasn't about to allow Zechariah's unbelief to get in the way
Who you respond when God make you a wonderful promise?