The Gospel to an outsider is a lot more about hellfire and endless political intrigue than it is about Jesus. In the mind of anyone raised in western culture Christianity means those who believe in eternal torment for non-believers. Once that idea is entrenched, Christianity can never be anything but a threat to those outside the church. Every word, every sermon, every ritual becomes an attack on the basic worthiness of every non-Christian. There is absolutely no mystery to why Christian Orthodoxy is reviled by many. And no, it is not because they are irredeemably bad people. They just see the so called Gospel for what it is, a threat sold as a divine gift.
The ineffectiveness of church evangelism has everything to do with their corrupted message and nothing at all to do with the flaws in the audience. The audience knows the church is more interested in putting sinners in jail, deporting them, or passing laws to define more sinners, than they are remotely concerned for the well being of those sinners. The self righteousness of the church is evident to all but those wallowing in it.