On the "exercise" of religion

As exemplified in last month's article in Harper's Magazine ("Jesus Killed Mohammed: The Crusade for a Christian Military"), some exercise of religion leads to evil consequences, and our Constitution's quashing of any law "prohibiting the free exercise thereof" [as it's phrased in the First Amendment] was ill-advised. The Constitution should have limited the "exercise of religion" to the confines of each person's own mind and private practice among consenting adults, the way various sexual activities are protected so long as they don't scare the horses.¹
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1. "My dear, I don’t care what they do, so long as they don’t do it in the streets and frighten the horses.” –attributed to Mrs. Patrick Campbell, British actress (1865-1940)
2. Or was it Lady Astor? At another website I found this quotation: "But it was Lady Astor, very much a Victorian, who said, 'You can do anything you like in public providing you don't frighten the horses.'"