God admitteth all men unto himself without exception, and by this means doth he invite them to salvation, as Paul gathereth in the tenth chapter to the Romans, and as the prophet had set it down before, "Thou, Lord, which hearest the prayer, unto thee shall all flesh come," (Psalm lxv. 2.)I don't expect this will silence the don't-confuse-me-with-facts-I-know-what-I-believe anti-Calvinist loonies* running around out there, but perhaps it will equip one or two of you with a useful response.
Therefore, forasmuch as no man is excluded from calling upon God, the gate of salvation is set open unto all men; neither is there any other thing which keepeth us back from entering in, save only our own unbelief. I speak of all unto whom God doth make himself manifest by the gospel. (Calvin's Commentaries, Vol. XVIII, p. 92)
*This refers to a subset of anti-Calvinists, not all of them. You know who you are. ;-)