I haven’t really thought much about the Establishment Clause, though I suspect I’m less ‘liberal’ on it than other provisions. His dissent in Engel v. Vitale had a good phrase too though:
‘I cannot see how an "official religion" is established by letting those who want to say a prayer say it.’ I’m quite surprised he and Harlan II were on opposing sides on the issue generally.
His dissent there is decent, but the height of his jurisprudence in dissents, in my opinion, is on
Abington School District v. Schempp. I’m rather surprised White didn’t join him in it, although I suspect he probably came to agree with Stewart there.
“If religious exercises are held to be an impermissible activity in schools, religion is placed in an artificial and state-created disadvantage.... And a refusal to permit religious exercises thus is seen, not as the realization of state neutrality, but rather as the establishment of a religion of secularism, or at least, as governmental support of the beliefs of those who think that religious exercises should be conducted only in private.”