Westminster Confession of Faith 29.8:
Although ignorant and wicked men receive the outward elements in this sacrament, yet they receive not the thing signified thereby; but by their unworthy coming thereunto are guilty of the body and blood of the Lord, to their own damnation. Wherefore all ignorant and ungodly persons, as they are unfit to enjoy communion with him, so are they unworthy of the Lord’s table, and cannot, without great sin against Christ, while they remain such, partake of these holy mysteries, or be admitted thereunto.
The Jerusalem Chamber 