(RNS) On a visit to southern Spain, I came across a centuries-old Roman Catholic church that had a large stone post with iron rings placed beside the church door.

It was the whipping post, where targets of the Spanish Inquisition were tortured in public and their blood stains left to frighten others into obedience.

Whipping posts, stocks, pillories and other instruments of public humiliation and suffering have been standard fare in human societies, but they have been used with special zeal when religion and crown, or religion and state, were making common cause in repression. Religion gave God’s imprimatur, the crown or state supplied torturers, and the sharing of repressive power left both institutions more powerful.

America has thought itself above such an unholy alliance, but some of the worst public-torture excesses took place against heretics and Sabbath-breakers in the American colonies and, with religion’s blessing, against slaves on into the 19th century.

When any institution tries to gain power through fear, corruption follows. The Church’s excessive use of torture, humiliation, shunning and economic reprisal didn’t end with the Inquisition. Its lingering impact helps to account for Christianity’s virtual collapse in modern-day Europe and in Quebec.

Modern Christian zealots play with similar fire when they combine evangelistic fervor, patriotism, and a conservative moral agenda into a single thrust for influence that relies on intimidation more than Scripture.

Further corruption occurs when gaining power through fear leads to alliances with repressive political and economic institutions. As Spanish prelates found in the 14th century, preaching venom against Jews carries more impact if the crown can be led to slaughter Jews. Senator Joe McCarthy portrayed his witch hunt as “a final, all-out battle between communistic atheism and Christianity” and thereby won strong support from Roman Catholics and evangelicals.

I don’t dispute the integrity of conservative Christians when they raise moral issues. We need impassioned debate on morality in an America mired in corruption, greed and selfishness.

But when any religious movement ventures into fearmongering, it undermines its moral character. When religious enthusiasts pounce on dissent, as both progressives and conservatives do, the dialogues we desperately need get stifled. When religion wraps itself in the flag, declaring patriotism to have a Christian accent, open discussion becomes even less likely.

Saturday’s strange scene in Texas — where a governor invited people to a Christian prayer day, then stoked both their heartfelt desire to pray for America and their fears that some dreaded other is taking America away from them — seemed a lot smoother than McCarthy’s demagoguery but not substantively different. Play to people’s fears, link their fears to religion’s supposed enemies, merge the two impulses, and get faithful people shouting for revenge.

All Christians — conservative and liberal alike — need to remember that Jesus gave just one new commandment: don’t be afraid. Don’t let fear turn your heart away from lepers or gentiles. Don’t use fear as a weapon. Don’t be afraid of God or of each other. Live without fear, and join hands in seeking a society where the darkness cannot use fear against us.

Yes, fear is rampant in our land now, and much of it for good reason. Christianity must not seek to exploit those fears to build its franchise or to make common cause with self-serving politicians. When Christians use fear as a weapon, they violate the gospel itself.

(Tom Ehrich is a writer, church consultant and Episcopal priest based in New York. He is the author of “Just Wondering, Jesus” and founder of the Church Wellness Project. His website is http://www.morningwalkmedia.com. Follow Tom on Twitter @tomehrich.)