Genevan Book of Church Order (1556): “[Covenant children are] contained under the name of God’s people … Remission of sins in the blood of Christ Jesus doth appertain unto them by God’s promise … Paul … pronounceth the children begotten and born (either of the parents being faithful) to be clean and holy [I Cor. 7:14] … The Holy Ghost assures us that infants be of the number of God’s people and that remission of sins doth also appertain to them in Christ … Almighty God [is] their Father. [They are] His children bought with the blood of His dear Son.”
Belgic Confession (1561): “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 believers than for adult persons; and therefore they ought to receive the sign and sacrament of that which Christ has 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, baptism is to our children. And for this reason St. Paul calls baptism the circumcision of Christ” (article 34).
Heidelberg Catechism (1563): “Are infants also to be baptized? Yes, for since they, as well as their parents, belong to the covenant and people of God, and through the blood of Christ both redemption from sin and the Holy Ghost, who works faith, are promised to them no less than to their parents, they are also by baptism, as a sign of the covenant, to be ingrafted into the Christian church, and distinguished from the children of unbelievers, as was done in the Old Testament by circumcision, in place of which in the New Testament baptism is appointed” (Q. & A. 74).
Second Helvetic Confession (1566): “We condemn the Anabaptists, who deny that newborn infants of the faithful are to be baptized. For according to evangelical teaching, of such is the Kingdom of God (Luke 18:16), and they are in the covenant of God (Acts 3:25). Why, then, should the sign of God’s covenant not be given to them? Why should those who belong to God and are in his Church not be initiated by holy baptism?” (chapter 20).
Canons of Dordt (1618-1619): “… the children of believers are holy not by nature but by virtue of the covenant of grace in which they, together with the parents, are comprehended. Godly parents have no reason to doubt the election and salvation of those their children whom it pleases God to call out of this life in their infancy (I Cor. 7:14; Gen. 17:7; Isa. 59:21; Acts 2:39)” (I:17).
God’s sovereign election governs the salvation of all whether they die in the womb or shortly after birth or of a good old age. The elect are saved and the reprobate lost as with Esau and Jacob chosen before birth. We have every right to expect the children of believers to be elect if they die at a young age-JK