I know that Jesus did not die on the cross so that i could just go to church on Sunday mornings. There is a very specific reason that the Father called me into knowledge of His Son. We know, because of so many references in the Scripture, that the reason we were created and why He saved us, was to bring Himself glory. ( a few being: Is 43:6-7, Jer 13:11, Psalm 106:8, Rom 3:23)
But there is a very unique and specific calling for me. One that He had in mind before I was even born. Paul and Barnabas were called out by His Holy Spirit for a specific mission.
Acts 13:2 "While they were ministering to the Lord and fasting, the Holy Spirit said, "Set apart for Me Barnabas and Saul for the work to which I have called them."
In that passage it does not say what the specific calling was on the two. But He had obviously told them. When Paul wrote some of the letters to the churches, he told what his calling was. (Rom 1:1; 1 Cor. 1:1; Gal 1:15-16)
Can you bring Him the most glory from your life without knowing a specific calling? Could Paul have been as effective in spreading the gospel if he had not received a specific calling?
He knew he was called to preach the gospel to the gentiles. He had his target, so he could stay on mark. That was how God wanted to glorify Himself in Paul.
Think of how much time we waste when we do not know our calling. We stand around not knowing what to do.
2 Peter 1:10b "Therefore, Brethren, be all the more certain His calling and choosing you;"
1 Thes. 5:24 "Faithful is He who calls you, and He also will bring it to pass."