In the Book of Luke, chapter 2, verses 10 and 11, we find:
"10 Then the Angel said unto them, Be not afraid: for behold, I bring you glad tidings of great joy, that shall be to all the people,
11 That is, that unto you is born this day in the city of David, a Savior, which is Christ the Lord."
In the plan of salvation, the incarnation of the Son of God, Jesus, the Christ, His life and death, and His subsequent resurrection are God's will and the plan executed - all because of and a result of disobedience on the part of mankind. God knew the plan was needed. God acted. Praise be to God for His infinite mercy and grace!