Chapter 8: Lord's Day 8
Section 24. Q. 24: How are these articles divided? A. Into three parts: God the Father and our creation; God the Son and our deliverance; and God the Holy Spirit and our sanctification.
Section 25. Q. 25: Since there is only one divine being, why do you speak of three: Father, Son, and Holy Spirit? A. Because that is how God has revealed himself in his Word: these three distinct persons are the one, true, eternal God.