"The next time believers tell you that 'separation of church ..." — Dan Barker quote meaning

The next time believers tell you that 'separation of church and state' does not appear in our founding document, tell them to stop using the word 'trinity.' The word 'trinity' appears nowhere in the bible. Neither does Rapture, or Second Coming, or Original Sin. If they are still unfazed (or unphrased), by this, then add Omniscience, Omnipresence, Supernatural,Transcendence, Afterlife, Deity, Divinity, Theology, Monotheism, Missionary, Immaculate Conception, Christmas, Christianity, Evangelical, Fundamentalist, Methodist, Catholic, Pope, Cardinal, Catechism, Purgatory, Penance, Transubstantiation, Excommunication, Dogma, Chastity, Unpardonable Sin, Infallibility, Inerrancy, Incarnation, Epiphany, Sermon, Eucharist, the Lord's Prayer, Good Friday, Doubting Thomas, Advent, Sunday School, Dead Sea, Golden Rule, Moral, Morality, Ethics, Patriotism, Education, Atheism, Apostasy, Conservative (Liberal is in), Capital Punishment, Monogamy, Abortion, Pornography, Homosexual, Lesbian, Fairness, Logic, Republic, Democracy, Capitalism, Funeral, Decalogue, or Bible.