Chapter 25 — Lord's Day 25
Section 66. Q. 66: What are sacraments? A. Sacraments are holy signs and seals for us to see. They were instituted by God so that by our use of them he might make us understand more clearly the promise of the gospel, and might put his seal on that promise. And this is God's gospel promise: to forgive our sins and give us eternal life by grace alone because of Christ's one sacrifice finished on the cross.