Ephes. 3:1-6 (ESV)
For this reason I, Paul, a prisoner for Christ Jesus on behalf of you Gentiles—  assuming that you have heard of the stewardship of God's grace that was given to me for you,  how the mystery was made known to me by revelation, as I have written briefly.  When you read this, you can perceive my insight into the mystery of Christ,  which was not made known to the sons of men in other generations as it has now been revealed to his holy apostles and prophets by the Spirit.  This mystery is that the Gentiles are fellow heirs, members of the same body, and partakers of the promise in Christ Jesus through the gospel.
The Stewardship of God’s Grace, Paul talks of his apostolic office as a stewardship, it is a responsibility he has to proclaim the mystery of Christ. Paul talks of this stewardship elsewhere in 1 Cor. 4, and Titus Chapter 1 extending this stewardship to all pastors. Perhaps the difference between a pastor and lay people is that where lay people can forgive sins, the Pastor has a responsibility to do so, where lay people can share the gospel with others, the pastor has the responsibility to do so. It is a great responsibility, sharing the mystery of Christ, the gospel in all its glory. Pastors have received from the apostolic office, if nothing else, this stewardship, this responsibility. It is laid on our shoulders, it is the yoke of Christ, and the reason for a stole.
The word mystery, here, was translated sacrament in the Latin. Biblically this word has been used for all the articles of faith, time and history have assigned to it special connotation referring to the Lord’s Supper and Baptism. I wouldn’t want to limit its use to those two sacraments by modern definition, neither would I want to exclude them they are mysteries, and fall under the special stewardship of pastors inherited from the apostolic office. But here the Gospel itself is referred to as the mystery of Christ. The mystery is that gentiles are fellow heirs, members of the same body (as Israel of the Old Testament) partakers in the promise of Christ. Salvation is for all regardless of ethnicity, or social status. We are all one body in Christ, saved by the same promise.