Authority to Baptize Children

The Church of Jesus Christ has the authority to baptize young children because of the continuity of the one covenant of grace.
God required the sign and seal of the covenant of grace to be placed on covenant children in the days of Abraham - circumcision.
God still requires a sign and seal of the covenant of grace to be placed on children in the days after Christ's circumcision - baptism.
By receiving the sign and seal of the covenant of grace, God is graciously giving our children a fuller declaration of the Gospel.