In Psalm 71, the psalmist says "You are my trust from my youth. Upon you I have leaned from birth.” 
In Psalm 22, David says, "You made Me trust while on My mother’s breasts.”
In Luke 18, believing parents bring their infants to Jesus for a blessing. Jesus laid hands on them and said, “To such belongs the kingdom of God.”
In Luke 1, John the Baptist was in the womb of his mother Elizabeth and Jesus was in the womb of his mother Mary. When John got close to Jesus, he danced for joy in the belly of his mother. John already knew and loved the Savior.
Jeremiah says God knew him and set him apart in the womb.
Paul reminds Timothy he had learned the sacred Scriptures from infancy.
Again and again we see not just that God loves the little children of his people, we see God is at work in them. Again and again Scripture points to God’s special covenant relationship with the children of his people, as he works in their hearts even before they are born.
That the psalms speak this way is especially significant because the psalter is the core hymnal of the church. God clearly wants his people to sing songs about growing up in the faith, trusting him even from infancy, never knowing or remembering a day when Jesus was not their Savior. That testimony should be normal for those born into Christian homes. Obviously those who get converted in adulthood have a different experience. But for covenant children, growing up Christian is normative.
We should not think of the experience of Jeremiah and John in the womb as unique. While there are specific features in each case (e.g., they will both be called as prophets, and that mantle is already upon them in youth), they prove that God can make himself known in a saving way to children even before they reach the age of reason or speech. The kingdom of God does not have a minimum IQ requirement. The kingdom of God is not like a ride at Six Flags with a minimum height requirement.
God’s love for the children of his people is a major theme in Scripture. Throughout Scripture, we find that God distinguishes these covenant children from children born outside the covenant. It is not that covenant children are less sinful; it is that God promises to work in them to counteract their depravity and bring them to faith from their earliest days. We sing “Jesus loves the little children” and it’s true — Jesus loves the little covenant children! He says they belong to his kingdom. He establishes a relationship with them as soon as they are conceived. They are objectively holy. They are given God's Spirit.
Precisely because covenant children have this special status, God in his word gives their parents special promises and special commands. The covenant in its totality, both promises and commands, should be the environment in which these children grow up. Thus: God commands these covenant children to be marked with a sign to visibly and publicly set them apart. That sign in the new covenant is baptism. God commands parents to raise these children — who are really his children — in the truth and nurture and admonition of the Lord. God makes promises to believing parents that his his mercy will be from generation to generation upon those who fear him; our children should be saturated in these declarations of Scripture, forming their identity. God makes promises to households, “I will be a God to you and to your children after you”; thus, every Christian father can say with Joshua, "As for me and my house, we will serve the Lord." God always embraces the next generation in covenant love.
Of course, the covenant is conditional. Promises must be believed and commands obeyed. Parents must set a godly example before their children, teach them God's Word diligently, discipline them with the rod in love, and pray with and for them continually. Likewise, children must persevere in the faith of their infancy; they must mature, "growing and becoming strong, filled with wisdom." Conditions do not nullify grace. Conditions are fulfilled by grace. Thus, there is no question that God's covenant is a covenant of love, mercy, and grace from beginning to end.
Because they believe these promises and desire to fulfill these commands, J and M bring P for baptism today and will now take these vows….