This is a fascinating question that I’ve received a lot (except to ask whether Buddhism is a religion of peace), so I’m eager to answer it at least in part. This is a topic the answers to which have been book length but I promise not to do that here!
Let me say this first. It’s important to figure out why we’re even asking the question. Often, I’ve had people ask me this question so that they can justify their fear (or even hatred) of “the other.” I’m certainly not saying you’re doing that Stewart! But you may run into some folks who are. But there are times (and I assume this is one of them) when we ask this question because we understand that religious violence is a fact of life and we need to find hope for an antidote somewhere. That’s where I think that an understanding of the gospel really helps, even though there is violence in the scriptures.
Some procedural points: When we ask the question about whether a particular religion is a “religion of peace” we have to define our terms. What do we mean by “religion” and what do we mean by “peace”? Take religion first. One might define “religion” as a set of core doctrines and beliefs as put forth in the foundational writings, teachings, and actions of the founder of that religion. Let’s call that Religion Definition 1. Another way to think of religion is more social: A set of beliefs and practices adhered to for the most part by a certain people group based strictly or loosely on the writings, teachings, and actions of the founder, but also heavily influenced by personal preferences. Let’s call that Religion Definition 2. You can easily see how these might be very different. Take Islam for example. By far, the vast majority of Muslims are peaceful people in the sense that they have no desire to “take over the world for Islam” or hurt anyone in the name of their religion. In fact, most Muslims are only nominally Muslims. They believe because of their heritage, not because they have any real knowledge about Islam itself. If we applied Definition 2 to the global scene, we could say that for the most part, Islam is a peacefully expressed religion. That would hold true of Buddhism as well and especially Christianity (or nearly every other religion).
But if we use Definition 1, our answer will be different. Islam specifically teaches, through its founders words and actions and the Qur’an itself, that violence is incumbent upon a Muslim against non-Muslims because of what they believe (See Sarah 9:5 and Surah 9:29 for just a few examples). Muhammad’s life, as told to us through Muslim sources in the hadith, is full of both peaceful actions and brutalities. So if we take Definition 1, then we see that it isn’t an inherently peaceful religion in terms of lack of conflict or violence.
The next term we have to define is “peaceful”. What do we mean? If we mean - not usually in the headlines for committing some atrocity, then we have some answers. Christianity is rarely in the headlines for atrocities, although Christendom is certainly not innocent of abuses. Buddhism isn’t usually in the headlines for violence and the like, but there are instances of it occassionally and even pervasively. Take for example the Buddhist killing of Muslims in Myanmar and other terrorism committed by Buddhists for political reasons (see the links HERE for but one story from the BBC on this). In fact, Time Magazine did an article on Buddhist extremism where the cover was a picture of a Buddhist monk with the headline, “The Face of Terror.” See it HERE
My point is that there is scarcely any religion that doesn’t have serious dark times in its past. As a Christian, I shouldn’t be surprised by this because the human condition is one marked by sin. Religion can often be a powerful tool for abusers. The question comes down to this: Is the violence done in the name of the religion consistent with the tenets of that religion? Does the violence we see have something to do with Religion Definition 1 of that particular belief system?
With Islam, the answer is yes. With Buddhism, the answer is a little less clear. While there has been violence committed in the name of Christianity, and we do see violence throughout the Scripture, I think that what we find is that some of the violence, especially the violence commanded by God, is warranted as a response to human evil.
I would recommend a couple of resources for your perusal. First is a serious of debates between David Wood and Shabir Ally on whether Islam or Christianity are violent religions (HERE and HERE). Second, I would take a look at the late Nabeel Qureshi’s book, Answering Jihad, where he points out some of the detail about Islam and violence.
Let me go to the gospel now. Yes, the scriptures contain violence and even commands for violence. Paul Copan and others have done masterful jobs at explaining the contexts and limited circumstances of such things. But I want to point this out by way of illustration about how the gospel can lead to hope in a violence-weary world.
A few years ago, I was doing a dialogue with an Imam at a major university. During the Q&A, someone asked us both this question: “Can you live consistently with the core teachings of your respective religions and be non-violent?” As a former Muslim, I responded by saying that “this is no longer a problem for me because I follow Christ, who shed no one’s blood but his own.”
I hope your discussions with your friend and others bear much fruit!