The rise of radical Islam is not directly a result of the 'moral vacum' created by the decline in Christianity - it is that level of arrogance about his faith that alienates the very people to whom the bishop should be reaching out.
The modern church is the same as the ancient church - isolated, elitist, superior, pompous, holier-than-thou (literally!) snobbish, deeply out of touch, and profoundly convinced of its own wonderfulness, such that it doesn't feel the need to actually proactively build its belief system, but feels it should simply allow its all-round wonderfulness to seep into the collective conciousness by osmosis, and then it bleats and moans when this fails to occur.
Radical Islam is the same as radical Christianity - a minority of insecure arrogant idiots who believe they are right, and the world is wrong.
The rise of Islam is simply a law of averages - if you build your faith into the fabric of your family life - as Islam does - then you will always have far more followers. This proportionately means ytou will have a greater percentage of fanatics - which although a small minority, are seized on by the right wing fear factory that is the western media, and made to be far more frightening and widespread that they really are.
The Bishop would do well the get his vicars out into schools and colleges and preaching the practical and positive aspects of his faith, instead of shouting down from his ivory tower about how we are all doomed, and it is nothing at all to do with him - he is a good guy, it's the rest of us who are going to hell in a hand cart.
The Christian church gets the followers it deserves - or as is apparent - not.