Psalm 31:24 Be of good courage, and he shall strengthen your heart, all ye that hope in the LORD
There is a connection between courage, strength and hope. Those who hope in the Lord should have courage because He will not disappoint our hopes. If we have a sure and certain hope in the Lord then we will also find courage in our hour of need. The wicked flee when no man pursueth: but the righteous are bold as a lion (Proverbs 28:1). Just as the lion fears no other creature those who place their trust and hope in the Lord will fear no other creature, either in the heaven, in earth or under the earth.
When David walked out to face Goliath the giant he found more courage than all of the armies of Israel even though at the time he was only a very young man. David placed his hope in the Lord and by so doing found courage to help in his hour of need.
We can be sure of God's promises because He is faithful who has promised. All of God's promises are yea and amen. For all the promises of God in him are yea, and in him Amen, unto the glory of God by us (2 Corinthians 1:20). Our Lord Jesus Christ is the faithful and true witness and so as we place our faith and hope in Him we will find Him always and entirely faithful towards us.