I liked the first part. I agree with his reasons for engagement and even interventionism as opposed to protectionism or quietism. I especially like how he acknowledges mistakes (of course).
However, as a former professional religious person, I can't let his comments about Islam (about half-way down) go by unremarked.
You can only interpret the Koran and fundamentalist Islam this way if you are postmodern and try really hard. There are two things at stake here. One is just plain reading and interpretation, faithful exegesis, regardless of your worldview. The second is an accurate understanding of religion.
Only in this age of Reader Response Theory and Deconstructionism could you make statements like this about historical Islam and the Koran. I see people on both sides of the Atlantic doing this, including President Bush. Historical Islam embraces jihad. The Koran says kill your enemies.
Are there more 'modern', 'liberal' Muslims? Yes. And they might be on board with what Blair's saying. But it's not 'orthodox'. What are the percentages of liberal versus fundamentalist? I have no idea. I'd guess there are more of the fundamentalists.
Saying that liberal Islam is the true Islam is ridiculous. It's only true if you have to see the world through a postmodern, let's-not-let-that-whole-Truth-thing-come-between-us paradigm.
I'm not saying fundamentalist Islam is the true Islam. It does have history on its side. But the whole discussion is more complicated than that. Oversimplifying it can only hamstring our understanding of the dynamics involved. Deploying is for rhetorical effect 'promotes' misunderstanding. Actually believing it is worse...
All of that said, I still agree with Blair's conclusion.
The extremism is not the true voice of Islam. Neither is that voice necessarily to be found in those who are from one part only of Islamic thought, however assertively that voice makes itself heard. It is, as ever, to be found in the calm, but too often unheard beliefs of the many Muslims, millions of them the world over, including in Europe, who want what we all want: to be ourselves free and for others to be free also; who regard tolerance as a virtue and respect for the faith of others as part of our own faith. That is what this battle is about, within Islam and outside of it; it is a battle of values and progress; and therefore it is one we must win.