although I was formerly a blasphemer, a persecutor, and an insolent man; but I obtained mercy because I did it ignorantly in unbelief.
1 Timothy 1:12-13 (NKJV)
Over the years, I have had several different jobs in various capacities. In some jobs, I was promoted to an oversight and leadership position. Sometimes, when I was first put into the position, people might ask me who put me into that leadership position and who gave me the authority to do what I was doing. Once I explained to people who it was that gave me the position I was in, things worked well. However, I was not able to just put myself into that position, someone else had to designate me as the person who would have that job with that company.
In 1 Timothy 1:12, Paul explained how God put him into the ministry, because God saw that he was faithful. God placed Paul into the spiritual leadership position that he held, even though, as Paul explained, he did not have a wonderful past. God put Paul into the ministry as He saw best, Paul did not place himself there, and Paul really could not have done that. Paul could have taken some ministry position or office, but without God actually placing Paul into the ministry, what Paul was doing would not have succeeded.
God has a plan and purpose for every person, and just like He did with Paul, God still places people into the ministry today. Paul's former life as a Pharisee, and the mistakes that Paul made, did not qualify, or disqualify Paul from what God had called him to do. Yes, Paul needed to be faithful in following God's plan for his life, but it was God who put Paul into the ministry. We need to discover the plan that God has for our life, and be faithful in it, allowing God to be the One who places us into whatever aspect of ministry He chooses to put us into, we cannot do that for ourselves.