The Catechism in Questions & Answers

4. How does God reveal Himself in history?

God reveals Himself in the history of mankind. For example, He led the people of Israel out of captivity in Egypt and gave them the Ten Commandments. The greatest of God’s revelations in history occurred when He became human in Jesus Christ and when He was active on this earth. He lived 2,000 years ago. God revealed Himself as the Redeemer in Jesus Christ.

Redeemer: see Questions 66., 108.-109.

“But when the fullness of the time had come, God sent forth His Son.”
Galatians 4: 4