“I delight to do thy will, O my God.”
Here are undeniable facts by which we know and are sure that Jesus is the Christ, the Son of the living God: ― He put an end to the sacrifices and ceremonies of legal worship by fulfilling them. ― He came into the world as Jehovah's voluntary Servant. ― And he fulfilled the volume of Old Testament prophecy to the letter. But I have saved the best until the last. Here is the greatest, most blessed assurance we have. By this, above all else, we know that Jesus our Savior is the Christ. ― David tells us that the Christ, the Messiah, whoever he might be, would perfectly accomplish the will of God ― "I delight to do thy will, O my God: yea, thy law is within my heart."
When the Lord Jesus came into this world, he came with delight to do his Father's will. He delighted in that of which God approves. He delighted in that which God had appointed. And the law of God was in his heart, so that both inwardly and outwardly, he was perfectly holy, harmless, undefiled, and separate from sin. He knew no sin!
We know that Jesus is Christ, the Son of the living God, because he perfectly performed all the precepts of God's revealed will in the law. By his obedience to the law of God as our Substitute, Representative and Surety, he brought in an everlasting righteousness for us. He freely yielded himself to all the performances of God's providential will. His unceasing submission to the Father’s will in all things is both our salvation and our example. How we rejoice in him whose prayer and heart’s desire was, "Not my will, thy will be done!" The Lord of Glory made complete satisfaction and propitiation to God's justice, satisfying the penalty of the law. In doing these things he accomplished the complete salvation of God's elect (Heb. 10:5-14).
Christ came to do the Father's will. He came to save his people. And he has done it. We know that Jesus is the Christ, because God accepted his work (Rom. 8:32-34).
How do we know that Jesus is the Christ? We know that Jesus is the Christ because he has fulfilled all that God said the Messiah would do. ― He put an end to legal sacrifices and ceremonies. ― He came into this world as a voluntary Savior, as Jehovah’s voluntary Servant. ― He accomplished all that the prophets said Messiah must accomplish. ― And he perfectly performed the will of God.
We know that Jesus is the Christ, the Son of the living God because he has been revealed in us by the power of His Spirit in saving grace. His blood, applied to our hearts, has purged our consciences of guilt. We prove his divinity, Messiahship, and saving power by faith. We trust him. “We believe and are sure that thou art that Christ, the Son of the living God” (John 6:69).