Article 34: Holy Baptism.
We believe and confess that Jesus Christ, who is the end of the law, hath made an end, by the shedding of His blood, of all other sheddings of blood which men could or would make as a propitiation or satisfaction for sin; and that He, having abolished circumcision, which was done with blood, hath instituted the sacrament of baptism instead thereof, by which we are received into the church of God and separated from all other people and strange religions, that we may wholly belong to Him whose ensign and banner we bear, and which serves as a testimony to us that He will forever be our gracious God and Father. 
Therefore He has commanded all those who are His to be baptized with pure water, in the name of the Father, and of the Son, and of the Holy Ghost, thereby signifying to us that, as water washeth away the filth of the body when poured upon it, and is seen on the body of the baptized when sprinkled upon him, so doth the blood of Christ, by the power of the Holy Ghost, internally sprinkle the soul, cleanse it from its sins, and regenerate us from children of wrath unto children of God. Not that this is effected by the external water, but by the sprinkling of the precious blood of the Son of God, who is our Red Sea, through which we must pass to escape the tyranny of Pharaoh, that is, the devil, and to enter into the spiritual land of Canaan. 
Therefore the ministers, on their part, administer the sacrament, and that which is visible, but our Lord giveth that which is signified by the sacrament, namely, the gifts and invisible grace; washing, cleansing, and purging our souls of all filth and unrighteousness; renewing our hearts and filling them with all comfort; giving unto us a true assurance of His fatherly goodness; putting on us the new man, and putting off the old man with all his deeds. 
Therefore we believe that every man who is earnestly studious of obtaining life eternal ought to be but once baptized with this only baptism, without ever repeating the same, since we cannot be born twice. Neither doth this baptism avail us only at the time when the water is poured upon us and received by us, but also through the whole course of our life. 
Therefore we detest the error of the Anabaptists, who are not content with the one only baptism they have once received, and moreover condemn the baptism of the infants of believers, who we believe ought to be baptized and sealed with the sign of the covenant, as the children in Israel formerly were circumcised upon the same promises which are made unto our children. And indeed Christ shed His blood no less for the washing of the children of the faithful than for adult persons; and therefore they ought to receive the sign and sacrament of that which Christ hath done for them; as the Lord commanded in the law that they should be made partakers of the sacrament of Christ’s suffering and death shortly after they were born, by offering for them a lamb, which was a sacrament of Jesus Christ. Moreover, what circumcision was to the Jews, that baptism is to our children. And for this reason Paul calls baptism the circumcision of Christ.