Rev. Angus Stewart
Many cite Acts 16:31: "Believe on the Lord Jesus Christ, and thou shalt be saved," as if this was all that Paul said to the Philippian jailor. However, the promise of the gospel in Acts 16:31 is not only that God will save believing heads of households (such as the Philippian jailor) but that He will also save their families: "Believe on the Lord Jesus Christ, and thou shalt be saved, and thy house." This is the bit that is so often left out.
But what does it mean that God promises to save the children of believers? Will He save all the children of believers head for head? Paul explains that, "They which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed ... that the purpose of God according to election might stand" (Rom. 9:8, 11). Thus God promises to save all the elect children of believers whom He chose in Christ before the foundation of the world (Eph. 1:4). Unbelieving heads of households, press into the kingdom of heaven mindful of the great promise of God that "thou shalt be saved, and thy house!" Believing parents, here is an "exceeding great and precious" promise (II Peter 1:4) to you: God will save your elect seed!
God saved the elect households of Adam and Eve, Noah, Joshua, the Philippian jailor and many thousands like them. Why does God save families? Because He is a family God as Father, Son and Holy Spirit. Thus He makes His covenant with families. He declared to Abraham, "I will establish my covenant between me and thee and thy seed after thee in their generations for an everlasting covenant, to be a God unto thee, and to thy seed after thee" (Gen. 17:7). Since Abraham is the father of all believers, Jew and Gentile, in both the Old and the New Covenant (Rom. 4:11), God's everlasting covenant is with us and our seed after us.
Because of God's promise to save the children of believers (Acts 16:31), our children are "holy" (I Cor. 7:14) and members of the kingdom of heaven (Mark 10:15). Thus, as the Westminster Confession puts it, "the infants of one or both believing parents are to be baptized" for "it is a great sin to contemn or neglect this ordinance" (28:4-5). This promise to believers that "thou shalt be saved, and thy house" (Acts 16:31) is vital in our day of rampant individualism, for it preserves Reformed churches from sliding into baptistic theology and fundamentalism.