The Belgic Confession of Faith
Article 33: The Sacraments
We believe that our good God, mindful of our crudeness and weakness, has ordained sacraments for us to seal the promises in us, to pledge the good will and grace of God toward us, and also to nourish and sustain our faith.
God has added these to the Word of the gospel to represent better to our external senses both what God enables us to understand by the Word and does inwardly in our hearts, confirming in us the salvation imparted to us.
For they are visible signs and seals of something internal and invisible, by means of which God works in us through the power of the Holy Spirit. So they are not empty and hollow signs to fool and deceive us, for their truth is Jesus Christ, without whom they would be nothing.
Moreover, we are satisfied with the number of sacraments that Christ our Master has ordained for us. There are only two: the sacrament of baptism and the Holy Supper of Jesus Christ.