XXIII. Of the Lord’s Supper
The Supper of the Lord is not only a sign of the love that Christians ought to have among themselves, one to another, but rather it is a sacrament of our redemption by Christ's death: insomuch that to such as rightly, worthily, and with faith receive the same, the bread which we break is a partaking of the body of Christ, and likewise the cup of blessing is a partaking of the blood of Christ.
Transubstantiation (or the change of the substance of bread and wine) in the Supper of the Lord, cannot be proved by Holy Writ, but is repugnant to the plain words of Scripture, overthroweth the nature of a Sacrament, and hath given occasion to many superstitions.
The body of Christ is given, taken, and eaten in the Supper, only after an heavenly and spiritual manner. And the mean whereby the body of Christ is received and eaten in the Supper is faith.
The Sacrament of the Lord's Supper was not by Christ's ordinance reserved, carried about, lifted up, or worshipped.
XXIX. Of the Wicked which do not eat the body of Christ, in the use of the Lord’s Supper
The wicked and such as be void of a lively faith, although they do carnally and visibly press with their teeth (as S. Augustine saith) the sacrament of the body and blood of Christ, yet in no wise are they partakers of Christ, but rather to their condemnation do eat and drink the sign or sacrament of so great a thing.
Complex metaphysical theories grew up around the Lord's Supper during the late Medieval era, which are reflected in the formulation of Articles 28 and 29. It was argued that the sacrament of the Lord's Supper has three parts: the outward sign, the inward thing signified, and the "virtue" or the excellence or worth of the sacrament. These articles basically assume this as their background. However, they reject the Roman Catholic position on transubstantiation, i.e. that the elements of the bread and wine physically become the body and blood of the Lord Jesus.
Nevertheless, it is evident here, as before, that the Thirty-Nine Articles tend to stay closer to Roman Catholicism than many other Reformed confessions. The Puritans in the Church of England did not appreciate this.