Contrast Mark 9 with Matthew 7

[Socialite]

Mark 9

38 “Teacher,” said John, “we saw someone driving out demons in your name and we told him to stop, because he was not one of us.”
39 “Do not stop him,” Jesus said. “For no one who does a miracle in my name can in the next moment say anything bad about me, 40 for whoever is not against us is for us. 41 Truly I tell you, anyone who gives you a cup of water in my name because you belong to the Messiah will certainly not lose their reward.

Matthew 7

21 “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but only the one who does the will of my Father who is in heaven. 22 Many will say to me on that day, ‘Lord, Lord, did we not prophesy in your name and in your name drive out demons and in your name perform many miracles?’ 23 Then I will tell them plainly, ‘I never knew you. Away from me, you evildoers!’

I want to be careful not to encourage these two scriptures to be used out of context. I understand the subject and audience were different -- but I'd be interested in commentary on the contrast between the two statements.