My sister and I are a lot alike. We grew up with the same parents, went to the same schools, grew up on classic rock, and we even love quoting the same movies together. We both have the same religious and political views (though she argues politics a little more intensely than I do), but at the end of the day we are not the same person. As much as we are similar we are that much more different.
A major difference is that she is a girl, obviously I am not. She was in the military, I love the military but cannot speak about it in the same way she can. I rock climb four days a week, she has been a few times but could not keep a conversation going on the topic. She works in the medical field, when I am around her work friends I feel like I am talking to aliens about things that happen on other planets. I love to write, her biggest writing samples these days are on Facebook about what she had for dinner.
If a brother and sister can have so many different experiences, how many more would you and your church friends have? This is an awesome thing. Our differences mean that we can relate to so many more people. My sister’s experiences lead her to places and people that I will never meet. So she has an opportunity to talk to people in a way that I cannot. Just as my experiences will lead me to people and places that your experiences will not.
This is what makes oikos evangelism so perfect. We are able to interact with the people in our oikos like no one else ever could. So instead of trying to reach everybody, try to reach the friends that you naturally have. If you are a police officer it is going to be natural for you to talk to other law enforcement, nurses are probably not going to be your natural group of people. Whereas someone like my sister can easily speak to a nurse (in alien language), and not be able to talk to the guy in your office that you work with everyday.
Trying to share Christ with everyone in the world can be quite intimidating. That is why it is the job of the entire body, not just a single member. When we focus on the 8-15 God puts in front of us, the influence can touch the world. I can share with my family and friends, who can then share with people I may never be able to meet. We are able to reach the world, one oikos at a time.