1 Tim. 2:5-7 (ESV)
For there is one God, and there is one mediator between God and men, the man Christ Jesus,  who gave himself as a ransom for all, which is the testimony given at the proper time.  For this I was appointed a preacher and an apostle (I am telling the truth, I am not lying), a teacher of the Gentiles in faith and truth.
“For this I was appointed a preacher and an apostle (I am telling the truth, I am not lying), a teacher of the Gentiles in faith and truth.” I put verses 5 & 6 with this verse so as to give it context. This is what all pastors and preachers of the Christian faith are called to preach. This is the gospel, this is what Paul means when he talks about preaching Jesus Christ, and him crucified, that on the cross Jesus mediated between God and man. So it is that for this, even I was appointed a preacher, though not an apostle.
It would be laughable, if it were not so blasphemous, that people today consider themselves apostles. You don’t just set yourself up to be an apostle. We consider those to be apostles who were eye witnesses to the resurrection, and were sent with an unmediated direct call from Christ himself to speak for him. We see these criteria being delineated in the first chapter of Acts! For people today to be calling themselves apostles blasphemous, it is perhaps the first indication that you should not be listening to a word they are saying. Even the partial bits and crumbs of truth that might fall from their lips can be found in greater quantities elsewhere. We tend to lose sight of what this word means, apostle. An apostle was a person who was basically given complete power of attorney for another person. One might think of them as an ambassador, but even that falls short. They had more free reign then an ambassador. A man employed as an apostle in the 1st century was able to marry, that is stand in on the ceremony, for the man who employed him. It isn’t just that they were sent, they were sent to speak and whatever they said it was as if the person who sent them said it himself. This is why it is also futile to try drive a wedge between the apostles and Christ.
Today we have no apostles, we have pastors. Apostles were pastors, the protopastor, but pastors aren’t apostles. Pastors though have been entrusted with the same message as that which the apostles were entrusted. So we are to teach that there is one God, and that there is one mediator between God and man, and that is the man Jesus Christ. He is our mediator, and by virtue of his death his mediation has been accomplished for all, we now have peace with God.