“Teaching them to obey” requires a life of obedience rather than conformity of beliefs.
Jesus is summoning people to follow him in total obedience and complete allegiance. As the One who had been given all authority, he was summoning His followers to submit to His lordship and to “disciple all the peoples” to submit to His reign/kingdom authority.
So teaching obedience to Christ’s commands actually extends His rule (kingdom) in the hearts of all peoples.
I was reflecting today about making disciples and the necessity of submitting to Jesus as one’s authority. Last year, one of the students that I had been discipling for over a year decided he didn’t want to follow Jesus anymore. He told me that He didn’t believe what the Bible said about not having pre-marital sex. Soon he was questioning everything he said that he believed.
Here’s the issue: he didn’t want to submit to Jesus’ authority in his life.
You can’t call Jesus “Lord” and then not do what He says. A follower of Jesus (Christian) will live a life in submission to Christ and His authority. And he or she will be actively engaged in helping others to follow Jesus in submission to His authority.