We see in this passage in Genesis 17:7 that God has always required the sign of the covenant to be placed upon those who dwell in the Household of God. In the Old Covenant, that sign … that mark … was circumcision. A bloody cutting of that agency which produces life. In the New Covenant, with all bloodletting being fulfilled by Jesus Christ, who was bloodily cut off as God’s agency which produces life, the sign of the covenant is now water which throughout Scripture speaks of life and purification.
So, the children of Reformed parents are Baptized with the presumption of charity as to their children’s covenant identity.
Following the conviction of “no neutrality” we understand that if we do not Baptize our children we are then presuming either they are not sinners and so have no need of the sign and seal of the washing of regeneration or we are presuming that our babies do indeed belong to their Father the devil and so are counted seed for Lucifer. Holding to neither of these presumptions, we presume, following Scripture, a charity regarding our children’s covenant identity and so following Scripture we baptize our children as God’s children.