Common sense often makes a good law.
The First Amendment, however, does not say that in every and all respects there shall be a separation of Church and State. Rathe, it studiously defines the manner, the specific ways, in which there shall be no concert or union or dependency one on the other. That is the common sense of the matter. Otherwise the state and religion would be aliens to each other.
The First Amendment makes confidence in the common sense of our people and in the maturity of their judgement the great postulate of our democracy.