Sometimes we merely have beliefs and sometimes we are attached to them. I am going to talk about the difference between having a belief and being attached to a belief. It's an important distinction. A lot of human misery is due to this attachment.
Let's start with a definition. From Wikipedia:
Belief is the state of mind in which a person thinks something to be the case, with or without there being empirical evidence to prove that something is the case with factual certainty. Another way of defining belief sees it as a mental representation of an attitude positively oriented towards the likelihood of something being true.For this discussion, it does not matter whether your belief is based on evidence or not. It does not matter whether it is due to the way you were raised, or what your friends profess, or the result of thoughtful analysis. For purposes of this discussion what matters is whether you have the belief without attachment, or whether you are attached to it.
We have beliefs, just as we have other things--money, clothing, cars. The important difference is this: no one can take or break your beliefs. Even your smallest belief is invulnerable to harm. Indeed, not even you can injure your beliefs. The only thing you can do is to replace a belief with a different belief, or with no belief at all.
Beliefs, unlike almost anything else we possess, are immaterial and invulnerable. We don't need to protect them and we don't need to defend them. So why do we defend them? I claim we don't need to, but we think we need to when we are attached to them; when we see our beliefs as part of ourselves; when we confuse who we are with what we believe; and when we confuse who others are with what they believe.
The difference between having a belief and being attached to a belief is how we react to challenges to that belief--or to attacks against it. If we can't stand apart from a belief, see it as invulnerable to any criticism, challenge, or attack--if we react to an attack against a belief that we hold as if it were an attack against ourselves, we're attached.
Some beliefs are good--that is, they lead toward better outcomes for most people. Some are evil--they lead to unnecessary harm. But having an evil belief, even being attached to an evil belief does not make a person evil. Nor does holding a good belief make one good. We are good or evil based on what we do and what we incite others to do, not merely based on what we believe.
Whether you view yourself through the lens of science as a conscious phenomenon or through the lens of religion as an immortal soul or being, you are also not a material thing. You may depend on a material thing--your body, or the universe, for your existence--but you are not it. So unless your body is being threatened or attacked, you are invulnerable as well.
Your body can be injured, but you can't be. And neither can your beliefs. So why do we feel threatened? Why do we feel a need to defend?
That felt need is a historical artifact, conditioned into us by our cultural experience. It is usually unnecessary in a civilized society. If you are in danger of being physically attacked, punished, or tortured because of your beliefs then defending your physical body makes sense. But defending your beliefs is always unnecessary. They don't need your help.
You can feel passionate about your beliefs, without being attached to them. You can encourage others to adopt your beliefs, or let others encourage you to adopt theirs without attachment. Your beliefs can stand on their own.
Sometimes it's hard to separate yourself from a belief. We say "that belief is part of me" or it's "part of who I am." But that's an illusion. A conditioned way of thinking, and an illusion.
Like all illusions, the conditioning is easy to break if you examine it. If you look, you can see that whatever you are (or are not) is independent of any belief that you might hold. If you look, you'll see that the idea that you need any particular belief or any set of beliefs in order to be yourself just can't be true. You are what you are (whatever that may be) regardless of what you believe.
The experience of consciousness is not based on any particular thought or idea. If you change your mind you don't become someone else.
If people threaten to harm you because of your beliefs or threaten to harm others because of their beliefs, you don't need to defend those beliefs. Instead, you need to challenge the belief of those who make threats that their threats are justified by what others believe.
It's their belief that needs to be challenged, questioned, and if need be, attacked.