This question haunted me for the first 2 years of our church. We didn't see anyone come to know Jesus in our services for the 1st 18 months, so I want to know the answer as much as anyone.
But here's what I learned: You can't change a culture (well, I guess you could, but it's next to impossible). However, it's much easier to create a new culture and let the old one die.
So the 1st step is to decide to create a new culture in your church. The next thing is to begin preaching the Gospel regularly. By regularly, I mean every week. This creates the awareness in those who attend your church that if they invite their friends, they'll have an opportunity to hear the Gospel and respond.
The other issue is to preach to your congregation about the importance of evangelism. A word of caution: the longer a church has been stagnant evangelistically, the harder this step and step 2 are going to be.
There's much more, but here's the bottom line: it's possible to turn things around if you're willing to pay the price and the take the appropriate steps.
If you want to know the steps we took at Calvary to create a culture of evangelism where over 1,000 people have made first time decisions in the last 18 months, check out our newest resource, "Creating a Culture of Evangelism" by clicking here.