To be more specific, I once was in a conversation with somebody about marriage equality. The other person couldn't give a single logical reason for why same sex couples shouldn't be allowed to get married. Ultimately, the other person just went with: "That's just the way I was raised." So, one can justify denying people their equal rights because it aligns with the values that you were brought up with? How does that make sense?
I sometimes get it lobbed at me that I'm "biased" when I reject supposed "evidence" for the supernatural. When I try to point out that the "evidence" that's being presented is either an anecdote, an argument from ignorance, or some other logical fallacy, that's when the accusation of bias comes out. If anything, I have a bias towards evidence-based reasoning, but I don't have a bias toward the supernatural not being real.
I suppose that I am biased against certain forms of supernatural belief systems. I don't particularly like the tenets of the Christian faith, and I not only don't believe them, but I hope that they're not true. However, when one embraces an evidence-based worldview, then one has to accept even the things that he or she doesn't like. For instance, I really, really, really wish that anthropogenic climate change wasn't real, and I tend to have a bias against things that get people all worried and panicky over things that might happen. However, it doesn't matter what my bias is; the evidence shows that it's happening. I also am biased in favor of the idea that alien civilizations are visiting our planet. The evidence doesn't match my bias though, darnit.
It especially doesn't make sense to me when people accuse me of not believing in a god because of my bias. I was raised to believe in God. When I started this journey, my bias was toward him existing. It's not that I decided one day to adopt a new bias; it's that I figured out that my bias wasn't justified. (Because sometimes they are justified. I have a bias against people who don't like The Beatles, and scientific evidence shows them to be untrustworthy.) Are there people who are so biased against any form of faith that they won't even hear the arguments? Of course. Are they so biased that even if God came down and gave a clear, unambiguous, verifiable sign that they'd still hold on to their nonbelief? I suppose so. But it's a mistake to assume that people don't reach the same conclusions as you simply because of a bias.
A bias is something that one should recognize and view as an obstacle toward discovering the truth. If anything, you look for things that would prove your bias to be unfounded rather than things that confirm it. That's easier said than done, and I like having my biases confirmed as much as the next guy, but I recognize that sometimes I need to at least hear the other side out in case my bias is taking me down the wrong path.