Romans 4: 20 & 21 KJV
20 He (Abraham) staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God.
21 And being fully persuaded that, what He (God) had promised, He (God) was able also to perform. We can only build our belief in God and know His promises through His word, The Bible. Then we can stagger not and be strong in faith, knowing that God stands behind His own Words.