The summary sermon, as usual, does not go into the many theological or sociological elements linked to the topic. The preacher may expand the topic where the congregation has the time and the capacity to delve more deeply.
The word "worship" carries quite a bit of baggage. In my evangelical tradition the tendency was always to move the word toward giving God His worth in our day to day life. This idea derives from Bible translators who have inadvertently used the word "worship" to translate the Greek word latreuw, "to serve", while at the same time using the word "worship" to translated the Greek word proskunew, "to adore, do obeisance." Also, puritans are by nature suspicious of form and always seek to reduce "color" in a church service.
In truth we should not abandon the word "worship" to describe a church service. All we need to do is emphasize the substance of the word, namely adoration. Nor should we be suspicious of form. It is absurd to argue that one form is holier than another. Frame is frame, shape is shape, none of it is eternal. Again, in my tradition, Reformed Evangelical Anglicans will often argue that abandoning Prayer Book liturgy, robes, etc. and replacing them with a happy-clappy pop culture alternative, is somehow more honouring to God and more able to further gospel ministry. To argue this way is to put weight on form, here a pop-culture form.
Many will argue that a church service is about education (teaching the word of God), or fellowship (making real our oneness in Christ), or evangelism (gathering in the seekers to bring them under the sound of the gospel). All these elements may be present in a service of worship, but I would content that the substantial business of a church service is to meet with Christ - to gather before him. In meeting with Christ the primary response is adoration, ie. worship. We should fall before him in awe and wonder.
The actual elements of worship are not hard to identify. In practical terms they involve, confession, thanksgiving, praise, the hearing of God's word, and prayer. One of the advantages of liturgy over a free-form service, is that the liturgist has the time to weave all these elements together. Yet, whether free-from or liturgical, there is always the danger that we rely on the frame rather than the inward motivations of the heart. It is easy to rest on form, rather than substance. Isaiah drives this danger home in this passage.
Although church growth principles tend to mitigate against a service beginning with a time of confession, it is the obvious starting point. What else can we do when we come before our Lord? We can only kneel again before His cross, making ourselves "clean before the Lord." The point Isaiah makes is that this show of humility can be devoid of inner substance. This danger lies with all the other elements of worship. It is the inner qualities we should work on, qualities such as renewal and love. The outward expression is nothing more than a frame upon which we hang reality.
So, we are best not to be over fussed by the frame, either innovating or preserving, as though it has substance, rather we are best to focus on the heart of the matter.