After the next workshop, you will be halfway through the program. Are there any topics you had hoped would come up that have not? Figure out a way to introduce them in the next two workshops.
Review the time line for the interfaith service project. Take care of any planning that needs to happen before the next meeting. Do you need assistance from the congregation? If participants have been less involved than you expected, set aside a few minutes next workshop to discuss their thoughts on the program generally and any suggestions they have for improving it.