To make things even clearer for your church members, you can have your calendars and events lists display only those events with images. You can also filter per the Google calendar you wish.
Part 1: Finding these filters
Step 1: After you log in, click on Calendars (brown box below).
The Your Calendars page will open.
Step 2: Choose the calendar or events list you wish to modify.
Step 3: If you are not already in the Setup tab, click on Setup (brown box below).
Step 4: Scroll down until you see Events Filtering.
Part 2: Selecting these filters
Toggle on the Show events with images only button (turquoise 1 in image above) to just show those item which have some sort of picture or other image. Read more + examples here.
Click on the downward arrow of the Calendars selection filter to open the dropdown menu (turquoise 2 in image above). Click on the Google calendar you wish to use.
Click on the blue Update button at the bottom to save your selections.