"Paul, an apostle of Christ Jesus by the will of God, To the saints in Ephesus, the faithful in Christ Jesus:" Eph. 1:1. NIV 
Paul, an apostle - Paul, who wrote most of the New Testament, probably never met Jesus while Jesus was on earth. Like us, his relationship with Jesus was all after the ascension. He had special visions and experiences because of what he was called to do, but all that shows is that Jesus will give us everything we need to accomplish what He has called us to.
Paul, in writing this letter, calls himself an apostle...Paul an apostle... He is not afraid to identify himself and his authority. This is what he is called to be and this is what he is without any false modesty, but also, without any false pride - he is an apostle not "the" apostle or the greatest of the apostles but "an" apostle - one in the group.
Paul identifies himself as an apostle, not a disciple. A disciple is a disciplined one, a learner, one who imitates the Master. We all disciples, even Paul, and none of us ever move beyond being disciples. For some there are additional callings along with being a disciple. Paul uses his calling as an apostle to show the necessary authority for writing this letter and instructing others. An apostle, while still a disciple, has the authority of Christ to teach others and to command their obedience on behalf of Christ. A disciple is primarily a learner. We will never move beyond the learner stage, but we will all have authority in different areas and at different times to practice what we have learned in ministry on behalf of our Master. For some, like Paul, the authority is a permanent ministry. For others, they function in the authority as needed. For example, some are given the permanent authority of a teacher. They teach on a regular basis and are recognized as teachers in the body of Christ, but all of us will teach from time to time, our children, our spouses, our friends. We will all share what we have learned as disciples.
of Christ Jesus - Paul is an apostle of Christ Jesus. He is not independent. He is not out on his own. He is a representative of Christ Jesus and under the authority of Christ Jesus. This means he is not only under the direct authority of Christ Jesus [which our human minds can often manipulate it into being whatever we want], but also under the authority of other human leaders who are appointed by Christ Jesus. He proved this several times by presenting his doctrine and life to the apostles in Jerusalem. Christ is the Greek version of Messiah, in other words, a title. Jesus is a personal name. Paul placed the "Christ" before the "Jesus" to emphasize that Jesus is the Messiah, the Saviour. The Messiah has come and His name is Jesus.
by the will of God - God has a will. He is not like the Deists proclaim - a God who started everything and then withdrew to see how it would work out. No, God has a will and a plan. He is actively at work in His world and His people. He works to see that His will is accomplished.
Paul became an apostle not because it was his desire or goal. He did not make a 12-step plan to become an apostle and then work at small steps every day until his goal was achieved. No, it was the will of God. God called Paul to be an apostle. It was God's idea, not Paul's idea. Because Paul was set in by God in the will of God, no one could remove him. When we strive for ministry in our strength and our own desire then we have to fight to keep it or maintain it. When God sets us is, He keeps us and maintains us.
To the saints in Ephesus - As an apostle, Paul is not responsible for everyone. He is responsible for those God has placed him over, including the saints in Ephesus. No one can be over everyone, but we all have someone we are leading, whether in the family or at work or in the church or… We must be faithful to those God has given us.
Saints are not just great men and women recognized as heroes by the church. Great heroes deserve honour, but they alone are not saints. Every believer, faithful to Christ Jesus, is a saint. They have had their sins washed away. They stand pure and holy before God - a true saint. Paul addresses them according to what he knew they were in the spiritual realm. He knew they were saints and he addresses them as such. Undoubtedly, he could have looked at their earthly lives and found much that was not saintly. Instead, he starts with who they are in God and who they are becoming on earth. We are all in the process. None of us have arrived, as far as the earthly manifestation of our life goes. These were real people in a real place in real circumstances. The Bible always meets us where we are at. God knows we are on earth in the midst of a sin-filled planet. He knows we struggle with issues in our lives.
the faithful - The saints are faithful - full of faith. To be faithful is to believe in someone, to keep your word to them and to be loyal to them. In order to properly be faithful to someone we must be full of faith in them. We can be faithful to Jesus Christ because we totally believe in Him and trust Him. We can be loyal until death. We can also be faithful to those He puts over us or around us even though, like us, they are fallible human beings because we have faith in Jesus. We know He is working through them even in their failures and shortcomings.
in Christ Jesus - Paul was an apostle of Christ Jesus. He belonged to Him and was sent by Him. The saints are in Christ Jesus, too. They stand with Jesus as their representative. They trust in His works, not in their own. They are surrounded by Christ Jesus on every side and protected by Him. God the Father sees them through the perfect righteousness of Jesus and loves them as He loves His own Son.