Yup, Korea's Patient #31 made things a lot worse, or else they would be doing much better right now.
The problem was so bad that, even before the current epidemic, other "regular" churches had a sign saying "No member of Sincheonji is allowed in our church." So, yeah, not exactly your garden variety Christian church.
When you think about it, this behavior would make Sincheonji a perfect vector for spreading the virus. And that's what happened. Yikes.