We’ve got to stop distinguishing between “missions” and, well, “not missions.”
The old paradigm was this: ministry is sharing the gospel. If you preached to believers, you were called a “pastor.” If you preached to non-Christians in your own culture, you were an “evangelist.” If you needed a passport to get there, you were a “missionary.” If those distinctions were ever helpful, they certainly aren’t today. Not when “the nations” are moving in next door and going to school with your kids. Not when there is yet to be an expression of Christianity that is truly free from modern rational humanism. We’re all missionaries because there is no “home.”
The division has resulted in “that’s not my job calling” on both sides of the divide. Many missionaries today see the church as a major distraction from their focus on evangelizing unbelieving people. Most churches outsource missions to a homely couple they send money to and pray for once a year.
The new paradigm is simple: all Christians are missionaries. They must be, because none of us are at “home.” Even if your ministry is to a group of people that you grew up with- a group that looks, talks, and acts just like you- you must recognize that your transformation in Christ necessarily makes you an outsider- a foreigner- to even your own culture. You can’t afford to assume that you are ministering in your own context. You don’t have a context in the world anymore.
Saying that all Christians are missionaries doesn’t mean we’re all good missionaries. Most Christians lack the skill, sensitivity, intentionality, and to truly be effective missionaries. Most Christians don’t worry about working to enter and engage culture because they think they’re already immersed in it. They may be, but the vast majority still step out of their cultures and subcultures and into an artificial “Christian” one every Sunday in order to worship and be discipled. We need missionaries.
If you are a Prius-driving, Lego-modding Starbucks barista, you’re uniquely qualified to be the missionary to that tribe. If you’re a Mac-using, soccer-mompreneur PTA member, your job is to incarnate the gospel among your people. It’s not enough for you to just try to fit in. You were saved to live out a Christ-transformed life in the midst of your social circles. You are where you are for a purpose.
There is no “home” and “foreign.” You are a missionary.

by E. Goodman (article here: http://missionsmisunderstood.com/2009/05/19/everyone-a-missionary/)