Tribes on Evangelism?

This next excerpt from Tribes seems to run contrary to what we believe is our Great Commission Mandate to spread the gospel to everyone.

Convincing people to switch tribes rarely works. To switch sides is to admit we made a mistake. You’ll find more fertile ground among seekers, among people who desire the feeling they get when they’re part of a vibrant, growing tribe, but who are still looking for that feeling.
If you’re trying to persuade the tribe at work to switch from one strategy to the other, don’t start with the leader of the opposition. Begin instead with the passionate individuals who haven’t been embraced by other tribes yet. As you add more and more people like these, your option becomes safer and more powerful – then you’ll see the others join you.

I learned some of this truth in a recent trip to a heavily Muslim area. I got into a really good conversation about the difference between Christianity and Islam. I've had conversations with cultural Muslims (Muslim in name but not in practice) and there was some interest in listening to talk of Christ without blindly defending Islam. But in this latest trip, I was talking to some staunch defenders of Islam and there was no amount of argumentation or propositional truth that was going to sway them. They had been trained to debate Christians. They raised all kinds of debate to the veracity of the Christian Scriptures. (They were doing this while they were making arrangements to sell pot in a local park!)
I was told by a missionary to an Islamic nation that he had never seen a Muslim converted based on any kind of Islamic evangelism techniques. That shows that it is hard to convince people to switch tribes. Not to say that it is impossible, but revealing the love of Christ and being consistent in your lifestyle in front of those you wish to join your "movement" is much more effective than convincing people to switch to your tribe.