God is not the author of evil and yet He ordains everything that comes to pass. To me it is more of a matter of His eternal being that we cannot understand in our finite and sin corrupted minds. He ordains EVERYTHING that comes to pass and His intention is to good and yet in our creaturely freedom we chase our own desires to sinful ends and evil. Ofcourse famous examples of this are the crucifixion of Christ (absolutely ordained by God yet carried out through the innumerable free will actions/choices of men) and the selling of Joseph into slavery by his brothers (their free choices were aimed towards evil at their brother... yet God intended it to save many during a time of great need)
Dr Gerstner says that we have to teach all that Jesus taught. It goes beyond that. Actually Jesus told to "teach to observe all that He commanded" Similarly to Deut. 6:6-9 that the commands must be in our hearts, that is to love them. The commission is not just to teach what He taught but (further) to teach them to love the Word of God and to train them to observe His commands.
