We must remain confident.

Isaiah 46:4
[The Lord says,] "Even to your old age and gray hairs, I am he, I am he who will sustain you. I have made you and I will carry you; I will sustain you and I will rescue you.

All throughout the ages God has made covenants and promises with his people and all His promises come through. Right in the beginning (Genesis 3:15) He promised that the serpent's head would be bruised by Eve's seed, that is Jesus Christ.

As promised, on the cross, Jesus gave the serpent a fatal blow to the head. Hebrews 2:14-15 says "Since the children have flesh and blood, he too shared in their humanity so that by his death he might destroy him who holds the power of death -- that is, the devil -- and free those who all their lives were held in slavery by their fear of death."

In other words, in the face of a terrible circumstance, the Lord looked at Adam and Eve and promised them and their seed (us) deliverance from the bondage they fell into. He has delivered this promise in Jesus Christ and not matter what we have done, we must remain confident in He who will crush satan under our feet and forgive our iniquities.