What's Mallard raving about today?
At first glance, there's nothing overtly objectionable today's panel. Until you notice the implication that Christians are the only persecuted religion in the world, failing to note that it all religions face similar persecution. Coupling that omission with saying that the predominantly Christian United States has offered safe haven for all religions, he's implicitly contrasting the nobility of Christianity with the barbarism of the rest of the world's religions.
And, thus, something as noble as the United States is turned into a cudgel to insult everyone else in the world.