Without the incarnation we would have no Savior. Sin requires death for its payment. God cannot die (according to the necessity of God and ontological rationale). So the Savior must be a human in order to be able to die.
But the death of an ordinary man would not pay for sin on an eternal level; therefore, the Savior must also be God. We must have a God‐Man Savior (Heb. 10:1‐10). If Jesus is not the Christ and had not risen from the dead (Rom. 1:4 affirms resurrection as an affirmation of divinity) then we are without a Savior still lost in our sin and our faith is in vain (I Cor. 15:17).
He must also be a God‐Man in order to be a sympathetic High Priest (Heb. 4:14‐16). Our High Priest can feel our weaknesses because He was tested as we are. But God is never tested, so it was necessary for God to become man to be able to be qualified to be a sympathetic Priest. The God‐Man must exist also in order to be a qualified Judge (John 5:22, 27). The Son of Man is given as a title to link Him to His earthly ministry and mission. Why must it be necessary for the Judge to be human and to have lived on earth? So that He may put down all excuses people may try to make. Thus the Incarnation has ramifications in relation to our knowledge of God, to our salvation, to our daily living, to our pressing needs, and to the future.