The largest mission field in the US is not the self-declared atheists or agnostics. It is not among professing Jews, Muslims, Hindus, Buddhists, etc. The largest mission field in the US is among self-professed Christians.
My own tradition recognized this. Look at what John Wesley said about the Methodist revival in England:
We look upon ourselves, not as the authors or ringleaders of a particular sect or party; (it is the furthest thing from our thoughts) but as messengers of God to those who are Christians in name, but Heathens in heart and life, to call them back to that from which they are fallen, to real genuine Christianity.
In Wesley’s time and place, the vast majority of England was Anglican — baptized and professing faith. But they were heathens in the ways that they lived and in the devotion of their hearts.
Is it enough for someone to say they believe in Jesus, or to have said a certain prayer, or to have “given their lives to God”? Are we just looking for them to say that they’ve acknowledged proper Christian beliefs with their mind? For the early Methodists, Christianity was a total devotion to God in heart and life. Claiming to have faith (i.e. agreeing to some propositions about religion) was not enough.
Perhaps when we think about evangelism, our first thoughts should go to Church-people, or former Church-people. A large mission field lies before us there.
Do you know anyone who has fallen away from the Church? Perhaps initiating a conversation with them is the place to start.
Do you know someone who claims faith but is, well, living like a heathen? Do you have opportunity to draw out the contrast of their professed faith and their life?
Though I’m generally a terrible evangelist, I have had some great opportunities by seeking out and asking professing Christians about their faith. Do you have opportunity to do the same?
Disclaimer: Don’t hear me giving the easy way out on this. I’m not saying that you can forsake all other evangelism until your weekly accountability partner has been perfected in faith.
teddy ray 
I wonder if part of the problem, here, is we don’t want to “lose” people by being honest with them about the sin in their life. If it is easier to act as though “everything is fine” than it is to help keep each other accountable.
I think you’re right about that being a problem, Shannon. And yet we are losing people regardless. That may be because if we’re not truly committed to fleeing from evil, the church ends up being either a group of people who agree to the same statements of belief or a social club of some sort.
Someone can agree to that list of beliefs from home. They don’t need the church for it. If it’s about a social club, it’s pretty easy to walk away when you’re not pleased with something. As a result, we have a number of people who claim Christian faith (i.e. they agree to the list of beliefs, probably were baptized, went through a confirmation) but have otherwise disappeared from the church.