Yet he did not waver through unbelief regarding the promise of God, but was strengthened in his faith and gave glory to God, being fully persuaded that God had power to do what he had promised. 

Romans 4: 20-21

The Greek word for waver is diakrino (dee-ak-ree'-no), which means to separate thoroughly, i.e. to withdraw from or oppose:- contend, doubt, judge, be partial, stagger, waver. 

Instead of wavering, Abraham was fully persuaded, plerophoreo (play-rof-or-eh'-o). This word means to carry out fully (in evidence), i.e. completely assure (or convince), entirely accomplish:--most surely believe, fully know (persuade), make full proof of.

You, too, can most surely believe and fully know that God has power to do what He's promised. 


*Strong, James, LL.D., S.T.D., The New Strong’s Expanded Exhaustive Concordance of the Bible, Red Letter Edition (Expanded With the Best of Vine’s Dictionary of Old & New Testament Words) (Nashville: Thomas Nelson, 2010).