The office or gift of the Pastor is listed among the gifts (often called the ministry gifts) in Ephesians 4:11. According to the scripture, those gifts are given by the Lord. Let us focus on the office of the pastor. It is the Lord who distributes these gifts as He sees fit. No man can choose to be a pastor. One cannot be a pastor by his personal choice. Doubtless there are many who are performing the role of the pastor, without the calling and, may be recognized by others as a pastor, simply on the basis that they preside over a church. But according to the scripture, presiding over a church is NOT what makes one a pastor. The callings of God are NEVER chosen by men. According to Hebrews 5:4, No man taketh this honour unto himself, but he that is called of God.
The scripture also says that the good works for which we are created in Christ Jesus were determined for us "before". (Eph 2:10). In Gal 1:15, 16 Paul states that it did please God who "separated me from my mother's womb and called me by His grace" to reveal His Son in him. This scripture implies that before he came out of his mother’s womb, his purpose was determined and that God brought him from his mother's womb for that predetermined purpose. In other words, a person is a pastor before he is even set over a church. He is set by God over a church because he is a pastor. He is a pastor before he had knowledge of it and certainly before he had a single member. The number of members over which one presides cannot be a basis to determining the call. Even having many members do not prove the call.