In The Book of Common Prayer (1662 & 1928) there is at the beginning of the services of Morning & Evening Prayer an Exhortation which declares concisely and with feeling the very purpose of the services. Indeed, the Exhortation may be said to give a general statement of the purpose of Christian worship. In 1662 it is compulsory while in 1928 it may be replaced by, "Let us humbly confess our sins unto Almighty God."

Let us go through it slowly and analyse it.

Dearly beloved brethren, The Minister presumes that the congregation is made up of fellow Christians who like him are loved by God the Father for the sake of his Son, Jesus Christ the Lord, and further that they are baptized believers.

the Scripture moveth us in sundry places to acknowledge and confess our manifold sins and wickedness; and that we should not dissemble nor cloke them before the face of Almighty God our heavenly Father; many times in the Bible the sinfulness of man is made clear and he is called not only to recognize and acknowledge his actual sins but also his internal wickedness. In the opening sentence of the service some of these biblical texts appear. Thus all those gathered for worship should not seek to hide or cover or escape from both their sins and the full acceptance of them before the all-searching eyes of God.

but confess them with an humble, lowly, penitent and obedient heart; after recognizing our sins and sinfulness and how these are offensive to the holiness and love of God, our clear duty is to confess them, not in parrot fashion, but in humility, repentance and with a view to obeying God in all things from the depths of our hearts.

to the end that we may obtain forgiveness of the same, by his infinite goodness and mercy. God our Father does not usually forgive his sinful and disobedient children unless they ask him in a suitably penitent manner. Later in this service of Morning/Evening Prayer, the declaration will be heard, "He pardoneth and absolveth all them that truly repent and unfeignedly believe his holy Gospel." And this Absolution and Remission of sins proceeds from the infinite goodness and mercy of God the Father for the sake of Jesus Christ.

And although we ought at all times humbly to acknowledge our sins our sins before God; yet ought we most chiefly so to do, when we assemble and meet together to render thanks for the great benefits that we have received at his hands, to set forth his most worthy praise, to hear his most holy Word, and to ask those things which are necessary as well for the body as the soul. The confession of sins is an essential part of worship for by it we acknowledge and praise the divine holiness, mercy and judgment. It is not a kind of preliminary that we must get over in order to engage in true worship for it is a part of true worship in spirit and in truth. Here it is recognized that true worship consists at least of (a) Penitence; (b) Praise and Thanksgiving; (c) The Reading of the Scriptures; and (d) Petitionary Prayers. And all these elements are to be found in the service which follows. God is praised through the chanting of Psalms and Canticles, his Word is heard in the lessons from the Old and New Testaments and the prayers occur at the end beginning with the Collect of the day/week.

Wherefore, I pray and beseech you, as many as are here present, to accompany me with a pure heart and humble voice unto the throne of the heavenly grace, saying after me: Thus the Minister invites all to join with him in the act of worship beginning with the confession of sins. It is important that they all proceed in the right spirit - a pure heart and humble voice.

In the version of Common Prayer that was proposed in England in 1928 but never accepted by the Parliament, this Exhortation was presented as a substitute for that in the 1662 Prayer Book.

Beloved, we are come together in the presence of Almighty God and of the whole company of heaven to offer unto him through our Lord Jesus Christ our worship and praise and thanksgiving; to make confession of our sins; to pray as well for others as for ourselves, that we may know more truly the greatness of God's love and shew forth in our lives the fruits of his grace; and to ask on behalf of all men such things as their well-being doth require. Wherefore let us kneel in silence, and remember God's presence with us now.

In the 1979 prayer book of the Episcopal Church, the Exhortation is shorter than in the 1928 BCP and changes the doctrine concerning the confession of sins (page 41). Here it is seen as being a preparation for worship, not a necessary part of worship, and this is a major change of doctrine and emphasis, with important pastoral repercussions.