"Not as the Scribes"

From the outset, Mark's gospel shows us that Jesus has authority.  He has authority over Satan (1:12-13), would-be followers (1:16-20), and unclean spirits (1:21-28).

His authority would become a source of conflict between him and religious leaders, including the scribes.  Early on, Mark introduces the conflict by noting that Jesus taught as one with authority, and "not as the scribes" (1:22).

The occasions for their conflict quickly mount: after he taught and handled an unclean spirit with authority (all as one piece, words and actions came together in a powerful revelation of who Jesus is), Jesus offended the scribes by eating with sinners and tax collectors (2:16), was accused by them of having a demon since he could exorcise (3:22), and was ridiculed for allowing the disciples to "eat with defiled hands" (7:5).

It's not enough that Jesus was doing battle with unclean spirits and the evil they represent or that he was battling with sin and its effect on lives, he also had to confront religious people because he was doing things in a way that didn't match how they'd do it.

Having experienced enough of that, Jesus was well-prepared for a scene later in Mark's gospel.  His disciples wanted to limit how good was done: 

38 John said to him, "Teacher, we saw someone casting out demons in your name, and we tried to stop him, because he was not following us." 39 But Jesus said, "Do not stop him; for no one who does a deed of power in my name will be able soon afterward to speak evil of me. 40 Whoever is not against us is for us. 41 For truly I tell you, whoever gives you a cup of water to drink because you bear the name of Christ will by no means lose the reward (Mark 9:38-41).

Rather than introduce another limited perspective on who was acceptable to represent him, Jesus was grateful for those who did.  Whether their hands were as clean as some would want them to be and even if their reputations were not sterling, Jesus was glad for their help as he sought to inaugurate the Kingdom of God.  When you are taking on adversaries like sin and evil, you don't get hung up on the small stuff, even when the small stuff is important to you.  Instead, when the adversaries are that large, you keep your attention where it needs to be: showing that the Kingdom of God come near and is taking back what rightfully belongs to God, whether that's "Tu-mah'," Bernard, or you (listen to or read my sermon from yesterday, if those references don't mean anything to you).