Keach on the Contradictions of Calvinist Paedobaptism

From Benjamin Keach, Gold Refin’d, or, Baptism in its Primitive Purity (London: 1689), 169.

Is it not strange men should say, all children of believers are in covenant, and that there is no falling from a state of grace; but that the New Covenant is so well ordered in all things, and sure, that it will secure all that are indeed in it, unto eternal life; and yet many of these children, who they say, are in this covenant, perish in their sins, dying unregenerate?