"It is not necessary for the true unity of the Christian church that uniform ceremonies, instituted by human beings, be observed everywhere." Augsburg Confession VII
"At the same time, however, the people are taught that such external worship of God does not make them righteous before God and that it is to be observed without burdening consciences, that is, no one sins by omitting it without causing offense." Augsburg Confession XXVI
The one thing that is necessary for a Christian to believe about the liturgy or pattern of worship which they follow, in order for it to be true worship, is that it is unnecessary.
This is not to say that baptism or the Lord's Supper are unnecessary. These sacraments are instituted and commanded by Christ Himself. But rites and ceremonies created by human beings, even pious saints, are not necessary.
And to say that they are is idolatry. To say that a pattern of worship drawn up by man (or even the one, holy, Christian, and apostolic Church) must be followed for salvation contradicts the words of Jesus Christ (Matthew 15:3-9).
In fact, to declare a rite, tradition, or ceremony created by man to be a necessity for salvation or unity in the Church makes it necessary for all Christians to deny this by their practice. "We believe, teach, and confess that in a time of persecution, when an unequivocal confession of the faith is demanded of us, we dare not yield to the opponents in such indifferent matters." (FC, E X)
But when we free the liturgy of the freight of having to be salvific, when we rightly recognize that following its forms and patterns will not make us righteous before God, we can actually use it for the reason it was intended: to direct our attention to Jesus Christ. We can practice the various forms that have been handed down through the ages, or modified by the church in more recent years, and rejoice in the Gospel truth that it imparts to us.
The moment we think that following a form of liturgy saves us we rob it of its power and content. The focus is moved from Gospel to Law, from the Son of God to the children of man. My performance becomes the center of attention rather than the person and work of Christ our Lord.
When we keep the liturgy as necessarily unnecessary we keep Jesus at the center, and that is where He belongs.