(RNS) Religion can do a great job helping believers discern right from wrong.

Religion can help believers relate kindly and justly to other people.

And religion can stiffen the will of believers when they face unjust suffering for their faith.

I was taught these things when I studied Christian ethics, and they continue to motivate me in my work as an ethics professor today.

But experience has me rethinking these claims more than I did at the beginning of my journey.

Now I see that religion can sometimes do a poor job helping believers discern right from wrong or relate kindly and justly to others. And religion can easily persuade people that the rejection they experience for their hurtful or ill-considered convictions is martyrdom for "God’s truth,“ leaving them even more entrenched in their destructive beliefs.

My two key teachers in the field of Christian ethics in the 1980s were the Baptist theologian Glen Stassen of Southern Baptist Seminary and the Lutheran ethicist Larry Rasmussen of Union Theological Seminary in New York.

These men knew each other and shared many common scholarly interests that shaped me as well. These included the Nazi period in Germany, the extraordinary life of the scholar-pastor-resister Dietrich Bonhoeffer, the challenge of overcoming racism and the fight against the nuclear arms race during the Cold War.

Both men modeled and taught me an essentially hopeful vision about the role that Christian convictions can play in making believers more faithful and society better.

They taught a faith that had learned the lessons of the Nazi period; that honored Bonhoeffer for standing fast against Nazi seductions when so many of his fellow Christians surrendered their souls; that resisted America’s own racism; and that rejected the idea that more nukes would make the world safer.

My own dissertation focused on that small minority of Christians who rescued Jews during the Holocaust. I sought to discover what kind of character, motivations and faith shaped these people who risked their lives when their neighbors were standing by indifferently. I have spent much of my career attempting to teach what I have sometimes called a “rescuer Christianity,” over against a “bystander Christianity.”

But now as a wizened old veteran of the fight, I struggle with discouragement sometimes. It is not just that many Christians fail to live up to the clear demands of Christian discipleship. It’s that we can’t even agree on what those demands are. We all say we believe in Jesus, but what we make of that belief is so irreconcilably different that I am not sure that we are in any meaningful way members of the same religious community.

I should have seen this more clearly all along. After all, could it really be said that Bonhoeffer, who died resisting Hitler, shared the same religion as the “Christian” men who murdered children in Hitler’s name?

What common religious values united white Christian members of the Ku Klux Klan and black Christians fighting for an end to segregation and lynching?

And how much do Islam-fearing, pro-torture Christians have in common with those who embrace interfaith comity?

A faith that stands with the crucified is very different from a faith that does the crucifying. The question becomes not whether you say you follow Jesus, but which Jesus you follow.

Worst of all has been my discovery in recent years of versions of Christianity that actually make people worse human beings than they might otherwise have been.

Here churches, pastors, or individuals interpret Scripture or faith in such a way that they do harm they would not do if they were just good old-fashioned pagans.

I never anticipated that I would think: “If we could just keep people out of (this version of) church, they would be better people.” 

Christian leaders often puzzle over why Christianity in America is declining so rapidly. Here’s a reason: Some highly visible versions of Christianity are so abhorrent that reasonably sensible people want nothing to do with it or the people who practice it.

The same, of course, holds for abhorrent versions of other religions. But that’s their problem, and this one is mine.