He staggered (wavered) not at the promise of God through unbelief; but was strong (strengthened) in faith, giving glory to God – Romans 4:20

Faith can be believing or doubting. Little faith can be a mixture of faith and unbelief. Faith can also be rooted in the promises of God.

God promised Abraham and Sarah that they would have a child in their old age. They were at the age of producing children, would have been impossible, but Abraham looked at the promise of God and not their age. His faith was rooted in the faithfulness and the ability of God. God works in the impossible, He works in situations and circumstance that seems to be out of reach of conquering. When faith seems to be failing, look back at the times when God delivered, when He healed, when He moved in your behalf.  Just as He came to your rescue then, He will come again, believing with the heart, moves the hand of God!