It’s a polite fiction that religion isn’t a factor in the American legal system. But religion plays an outsize role, both in judicial decisions and in the decisions of presidents in nominating a judge. President Donald Trump’s latest pick for the Supreme Court, Judge Brett Kavanaugh — a Catholic, whose appointment preserves the Catholic majority on the Supreme Court — will shift the high court dramatically to the right, most noticeably when it comes to religion.
Accordin...