Many controvert all the positions which we have laid down, especially the gratuitous election of believers, which however cannot be overthrown. For they commonly imagine that God distinguishes between men according to the merits which he foresees that each individual is to have, giving the adoption of sons to those whom he foreknows will not be unworthy of his grace, and dooming those to destruction whose dispositions he perceives will be prone to mischief and wickedness. Thus by interposing foreknowledge as a veil, they not only obscure election, but pretend to give it a different origin.
Sproul, R.C.; Grace Unknown: The Heart of Reformed Theology; Baker Books; Grand Rapids, MI; copyright 1997; p. 161