You can embed any online calendar that your ministry uses. This tutorial will show you how to embed a Google Calendar. If your ministry currently does not have an online calendar you can set up a free Google calendar by going to google.com/calendar.
Once you have set up your online calendar make sure your calendar is set to public
You can now copy the iframe code from the Calendar Details tab
Press the HTML button in the text box that you want your calendar embedded to
Paste in your iframe code from Google and Publish the page