Why infant baptism matters (Calvin's Institutes, Battles edition: p. 1359, vol. 2)

As he so frequently does, John Calvin points us back to gratitude for God's goodness in 4.16.32 of his Institutes:

Now I think no sober person will be in doubt how rashly they stir up Christ's church with their altercations and contentions over infant baptism. But it behooves us to note what Satin is attempting with this great subtlety of his. He is trying to take away from us the singular fruit of assurance and spiritual joy which is to be gathered from it, and also to diminish somewhat the glory of the divine goodness. For how sweet it is to godly minds to be assured, not only by word, but by sight that they obtain so much favor with the Heavenly Father that their offspring are within his care? For here we can see how he takes on toward us the role of a most provident Father, who even after our death maintains his care for us, providng for and looking after our children. Should we not, following David's example, rejoice with all our heart in thanksgiving, that his name may be hallowed by such an example of his goodness (Ps. 48:10)? It is precisely this which Satan is attempting in assailing infant baptism with such an army: that, once this testimony of God's grace is taken away from us, the promise which, through it, is put before our eyes may eventuallly vanish little by little. From this would grow up not only an impious ungratefulness toward God's mercy but a certain negligence about instructing our children in piety. For when we consider that immediately from birth God takes and acknowledges them as his children, we feel a strong stimulus to instruct them in an earnest fear of God and observance of the law. Accordingly, unless we wish spitefully to obscure God's goodness, let us offer our infants to him, for he gives them a place among those of his family and household, that is, the members of the church.