'The Order for the Administration of the Lord's Supper or Holy Communion' is not specifically discussed in the prefaces of the Prayer Book, but something of its theological significance is set forth in Articles 25-31. It is important to read these to get a full picture of the biblical and Reformed theology reflected in the liturgy. These are printed as 'The Articles of Religion' at the back of the Prayer Book and in modern versions
Only two 'sacraments' are recognised as having been ordained by Christ, namely Baptism and the Lord's Supper. These are described as 'badges or tokens' of our profession to one another, and also as certain sure witnesses, and effectual signs of grace, and God's will towards us, by the which he doth work invisibly in us, and doth not only quicken, but also strengthen and confirm our faith in him.' There is thus a horizontal and a vertical dimension to these ordinances. The unworthiness of ministers does not hinder the effect of a sacrament, 'because of Christ's institution and promise'. Critically, these 'signs of grace' must be received by faith.
The Lord's Supper is described as 'a sign of the love that Christians ought to have among themselves one to another', and also as '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' (1 Corinthians 10:16).
Various aspects of Medieval Catholic teaching are denied, such as transubstantiation (the supposed change of the substance of the bread and wine), and the sacrifice of masses (the view that the priest offers or re-presents the sacrifice of Christ to the Father). Positively, it is claimed that, '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.'