2 Cor. 11:13-15 (ESV)
For such men are false apostles, deceitful workmen, disguising themselves as apostles of Christ.  And no wonder, for even Satan disguises himself as an angel of light.  So it is no surprise if his servants, also, disguise themselves as servants of righteousness. Their end will correspond to their deeds.
I think it is much too often that we assume since one is using the name of Jesus Christ, they must be doing his work. They often quote the interchange between John and Jesus ins Luke 9: “John answered, "Master, we saw someone casting out demons in your name, and we tried to stop him, because he does not follow with us."  But Jesus said to him, "Do not stop him, for the one who is not against you is for you." (Luke 9:49-50 (ESV)
However, there is plenty in scripture that tempers this statement of Jesus. Just because a person is using the name of Jesus, does not mean he is for you, and not against you. Paul certainly would put an end to the false apostles. Satan’s servants often disguise themselves as apostles of Christ. I even recall a meth addict who claimed to be an apostle of Christ, trying to stop me from talking to one of the sheep Christ has entrusted to me. That man cursed me in the name of Jesus. That is obviously an extreme example.
But it is often the case that people use the name of Jesus, and the example of Jesus to actually turn one away from Jesus and focus them on their own navels rather than the cross. These people are not for Christ. “Their end will correspond to their deeds.” Perhaps this is why Jesus said what he said to John. It isn’t for us to burn heretics at the stake, throw them in prison or anything of the like. We do have an obligation to expose them, to proclaim the Gospel and contrast it to what they say, as Paul does. But ultimately they will answer for themselves. Perhaps in the meantime Jesus will even use these false apostles, He used Judas too.