This may not be true for your church, but it is for the few that I have attended in the last decade. Every so often, the pastor will get on a streak about evangelism and preach about how my main purpose in life should be sharing the gospel with other people. That's a problem, because it's not biblical and it's not true. Clearly, the main purpose of any Christian's life should be "to do the good works" that God has made for them to do (i.e., be obedient to Christ; walk with the Lord). But to say that evangelism is the good work that we should all be doing is unbiblical. Sharing the gospel is "the mouth's" job in the body of Christ (the Church), but we are not all "the mouth" as it says in the book of Corinthians. Any time a pastor starts telling me that my main priority in life should be sharing the gospel or inviting people to church or becoming a missionary, I want to stand up and remind them of that. Granted, there are some people who need to hear that message because it is God's work for them to spread the gospel, but to tell everyone the same message would be wrong. The Great Commission was given to the Twelve Apostles directly, not to the entire body of Christians. As for me, I will continue to do the good works which God has set out for me to do.
The mission of the Body of Christ, given by Jesus, is to make disciples all over the world and to care for each other (the Body caring for the Body).
Every member of the Body of Christ has a role in what the Body does, just as every member of a human body has a role in what the Body does.
But, yes, Paul teaches that not every one is an apostle, not every one is a teacher, et cetera. In 1 Peter, it repeats this:
Each of you should use whatever gift you have received to serve others, as faithful stewards of God's grace in its various forms. 1 Peter 4
This is kind of like a US Navy aircraft carrier. Now, the mission of an aircraft carrier is to use aircraft to take war to the enemy.
There are about 5,000 sailors on an aircraft carrier. Of those 5,000 sailors, only about 75 (seventy-five) actually get into airplanes to take war to the enemy.
The remaining 4,025 sailors do a hundred different jobs that support the 75 who fly airplanes.
If you were to ask the captain, "You have 4,025 sailors on your aircraft carrier who don't even fly aircraft! Can't you do without some of them?"
He'd answer, "Not on your life! Everyone one of my sailors has a mission-essential job to do every day."
Some of the sailors on that carrier do nothing but wash clothing. They wash the sheets, underwear, shirts, and trousers of all the other sailors. That's all they do, seven days a week (no weekends off at sea). That seems a long way from "taking the war to the enemy," but if you think about an aircraft carrier out in the Arabian Sea for six or eight months,
somebody needs to be washing sheets and underwear. And scrubbing the toilets, and cooking the meals, et cetera.
The Body of Christ works the same way. Each one of us is intended to have our own fragment of the Great Commission. We should know what it is, and we should be diligent in executing it.
Not every Christian is an evangelist. When we look at the New Testament, we see this model for evangelism:
1. The evangelist is called to that office by the Holy Spirit
2. The evangelist is thoroughly trained in the gospel by teachers in the Body.
3. The evangelist is commissioned by the congregation for a particular evangelistic mission.
4. The evangelist is accountable to the congregation that commissioned him, and must report back to them.
But while every Christians is not an evangelist, every Christian
is obligated to give reason for the hope he has within him.
There is a difference between evangelism and witness:
Evangelism is telling people what Jesus did for
them.
Witness is telling people what Jesus did for
you.
The Samaritan woman at the well provides an example: Jesus evangelized; the woman witnessed.
The woman then left her water pot, and went her way into the city, and saith to the men, "Come, see a man, which told me all things that ever I did: is not this the Christ?" Then they went out of the city, and came unto him. -- John 4
Notice that the woman didn't need to know theology. She didn't even know for sure that Jesus was the Messiah. All she knew was what Jesus did for her, but that shaky witness was enough to bring the whole town to Jesus.
Another example is the blind man healed by Jesus:
He replied, "Whether he is a sinner or not, I don't know. One thing I do know. I was blind but now I see!" -- John 9
Knowledge of theology: Zilch. Knowledge of what Jesus did for him: Nobody could take away his witness.
So, we should each know and perform our particular fragment of the Great Commission, generally through our own congregations.
And we should each be ready to give witness to what Jesus has done specifically for us in our own lives.