The normally sound and enjoyable Ezra Levant kind of went off the rails with this one.
He is a Jew and therefore evaluates life through the prism of the religion he was taught. Not for him is there any concern that in public institutions: universities, schools, governments, and other taxpayer supported or subsidized entities, the God of the Christians still reigns supreme. This country is not supposed to have a state religion, but, when you add up all the public places that God and his alleged will intrudes, there is a de facto state religion if not de jure one, and that religion is Christianity.
Why should a mild bus banner campaign bring out accusations of cowardice simply because atheists identify Christians as their major opponents?
He is right that the message is to prick Christians, but he is wrong to think that there is no point in doing so. Christians are the majority in this country, by a long shot (70%), and they call the shots. Islamic radicals are few in number and don't have much political clout or significant public support. Not so Christians.
When atheists finally get what they need from the Christian majority, which is to say, respect, then we will turn our attention to radical Islam.
As Abraham Lincoln concluded, when it looked like the U.S. might end up fighting Britain during the Civil War, "One war at a time."
Christians are more afraid of atheists than they are of anything else and if Ezra is really that concerned about challenging radical Islam, he might want to take some time off from bashing his fellow Jews (and now atheists) and ask the more interesting question of why Christian leaders pay such deference to Islam, but spend most of their political capital fighting atheists.