A faith that overcomes is a faith that believes in Jesus and what he has done for us through the finished work at the cross. Jesus is the author and the finisher of our faith. With our focus on Jesus, we have the victory in any situation.
I Corinthians 15:57
But thanks be to God, which giveth us the victory through our Lord Jesus Christ.
I John 5:1,4
1. Whosoever believeth that Jesus is the Christ is born of God: and every one that loveth him that begat loveth him also that is begotten of him.
4. For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith.
Hebrews 12:2
Looking unto Jesus the author and finisher of our faith; who for the joy that was set before him endured the cross, despising the shame, and is set down at the right hand of the throne of God.