Romans - Unshakeable Faith

"Who against hope believed in hope, that he might become the father of many nations, according to that which was spoken, So shall thy seed be. And being not weak in faith, he considered not his own body now dead, when he was about an hundred years old, neither yet the deadness of Sarah's womb: He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God; And being fully persuaded that, what he had promised, he was able also to perform." Roman 4:18-21