March 28, 2014|3:35 pm

Ligonier Ministries Q+A (Screenshot: Ligonier Ministries/Vimeo)

During the Q&A session of the Ligonier Ministries 2014 National Conference, this question was submitted:

"Both of my brothers are unsaved. One believes there is no such thing as sin; therefore there is no need for a savior. How do I answer this question? How do I explain sin?"

Theologian and Ligonier Ministries founder R.C. Sproul chimed in a three-word tip that got the crowd roaring in laughter, but in its own way makes incredible sense.