They arrived at that conclusion because of something Jesus said to His disciples after the resurrection: "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you."
As believers in Christ living inside of a new and better covenant ... is it the goal for us today to work at following everything Jesus shared with His disciples or charged them to do? It seems like a simple answer, after all, we're talking about the red letters, right? But let's consider the bigger context of what that would mean if we were to work at applying every syllable found in each Bible verse containing the words of Jesus.