Mark 11:23 (NIV) I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and DOES NOT DOUBT IN HIS HEART but believes that what he says will happen, it will be done for him. You can have doubt in your head and faith in your heart at the same time. But what do you do with the doubt in your head? 1) Proverbs 3:5 - Trust in the Lord; Do not lean on your own understanding. 2) 2 Corinthians 10:5 ...take captive every thought to make it obedient to Christ. Have a wonderfully blessed day!