How do we know that Christ's incarnation was necessary?

The necessity of Christ's incarnation is explained in the sermon as being foundational for establishing righteousness for His people. As stated in Galatians 4:4, God sent His Son, made of a woman, to redeem those under the law. Because mankind cannot establish righteousness on their own, the God-man Jesus Christ fulfilled this requirement by living a perfect life and then making atonement for sin through His sacrifice. Thus, His becoming flesh was vital not just for God's revelation but also for our justification in Him.