On your home page you linked to, I see the following Open Graph tag:
<meta property="og:description" content="A community of believers focused on the commission of Jesus Christ, to baptize and make disciples of every nation. All are welcome! Visit our site to learn more."/>
Open Graph tags are what Facebook uses for their description. The twitter:description is for Twitter, but has the same value.
In either case, the tag I posted above looks like what you want to be set.
If you're still seeing the wrong value, please run your page through the
Facebook Open Graph Debug Tool
or the
Social Debug
tool to see what's seen on your page when it's scanned. That may help find where the incorrect text is coming from.
Thanks,
Alex