Because people are deceived, and it's hard for them to come to grips with that. I actually go soul winning door to door, and probably 9/10 people who claim the name of Christ, aren't actually saved. And most people don't even want to take ten minutes to have the Gospel clearly explained to them. And for the dozens of people I have seen saved, who have been in church for years, not one has actually started attending our church after we got them saved.

People who have been in church for years, and never were saved. Yet they continue to go to a church that didn't preach them the doctrine of Salvation through faith alone. Why in the world would people keep attending a church that gives no salvation? Because people are stubborn. Thankfully we don't go soul winning to fill the church, we do it to spread the Gospel. Which is why so many churches don't go soul winning. It doesnt fill the church and bring in tithes.