Balance refers to the placement of various elements in the worship space. Your church may have formal or informal balance. This is important to recognize so you are consistent when you introduce new visuals.
This is the sanctuary in my home church. Not only is the architecture formal but so is the balance. To maintain this balance we wouldn't want to hang just one Carrot Top Studio banner. Two banners keep the balance.
Repetition of a form or a shape creates a pattern. When patterns are small we call them textures. Patterns can enrich a surface, but they can also dominate and become loud or boring. Repeating pattern creates unity. This applies to the architecture like we've referenced but can also apply to the stoles worn by ministry leaders. The repetition of all the ministry leaders wearing the same stole (or at least the same color stole) creates unity and gives a visual impact that makes a great statement.
Variation creates interest. Too little variation makes a boring space; too much may make the space appear chaotic.
For example, the variation of the red banners against the white wall is enough in this chancel. The curved architectural trim around the banners and stained glass window smartly echos the front shape of the chancel. It the trim had been painted an accent color it would have been too much variation.
Contrast is needed to make certain elements stand out. If we're very used to our worship space it can be hard to see the contrast. A good tool is to take some photographs of the space and see what stands out. It's interesting to see what we notice in a photograph that we hadn't paid attention to before.
Harmony deals with how all the elements in the worship space work together. Is there anything fighting for attention? Color can actually be the tool that unifies. Whether you follow the liturgical seasons or not, if the color that is the accent for worship carries from altar cover, to Bible book mark, to worship banner to stole then you will most likely have created harmony.
The use of this table cloth creates harmony. Despite the use of many colors in the table cloth the repetition of red from the chair cushions, to the pew cushions to the carpet helps to create harmony. Does this make or break our faith? Of course not! But visual harmony can help us focus on what is most important--the worship of our Lord and Savior. If there isn't visual harmony our minds and hearts might not rest for the worship...at least for those of us that are visual learners.
Keeping in mind the principles of design as we look at our worship space will help to make sure the elements are supporting each other and not dominating. And in turn the space will call attention to God, not itself.