when is it too far

My sister invited a couple from her church over for dinner.
After the meal my sister asked if they wanted to start on dessert.
The couple looked at each other.
Wife: well.. we were wondering if we could share a spiritual thought.
They then proceeded with a prepared talk and ended with music they brought on a CD.
"I guess I should have seen it coming," my sister later told me. "When we ate at their house we went around the table saying what we were thankful for. Each one of us said our spouse and our family. I thought about doing a one up and mentioning the church and God..."
"It would only end in blood," I assured my sister.