What is confirmation?
Confirmation is a public rite of the church preceded by a period of instruction designed to help baptized Christians identify with the life and mission of the Christian community.
Note: Prior to admission to the Lord's Supper, it is necessary to be instructed in the Christian faith (1 Cor. 11:28). The rite of confirmation provides an opportunity for the individual Christian, relying on God's promise given in Holy Baptism, to make a personal public confession of the faith and a lifelong pledge of fidelity to Christ.
"Whoever acknowledges Me before men, I will also acknowledge him before My Father in heaven. But whoever disowns Me before men, I will disown him before My Father in heaven." Matthew 10:32-33
"Be faithful, even to the point of death, and I will give you the crown of life." Revelation 2:10
From An Explanation of Luther's Small Catechism, question number 306.