In any religious debate, you're likely to hear about "bias". "You only believe this because you're biased", "you're only saying that because you're biased", "only those who share your bias will be convinced by that argument". The truth is, everyone is biased, no matter how reasonable that person may be. But some people are unreasonably biased.
One way to tell someone is unreasonably biased is when they can't respect the strength of their opponents' worldviews. We often hear from atheists "there's no evidence for Christianity". Really? Apparently, there's enough evidence to convince former atheists that Christianity is true, so it seems strange to say there's no evidence.
By contrast, any reasonable Christian should be able to level with atheists on some things. For example, why doesn't God show Himself? It's an awful argument, and there are answers to it, but surely we can grant that if you don't believe in God, and don't understand theology, you might wonder why He doesn't show up? Heck, many Christians struggle with this concept, so even though it is a poor reason for rejecting belief in God, especially in light of all the evidence that yes, there is a god, and yes, He is the God of the Bible, we ought to admit that yes, there is some merit to atheism.
I admit my bias. Even typing the words "there is some merit to atheism" makes me feel strange, because atheism is not a philosophy I can take seriously. Nevertheless, although atheism is utterly irrational, I can understand why some people need help seeing that. Why, then, are some atheists so swallowed by their bias that they can't see why the Cosmological Argument, the argument from reason, or the historical evidence for the resurrection, convince us to be Christians? Either they are so blind to their bias that they can't see it, which is irrational, or they are so unwilling to come to Christ that they deny the existence and implications of that evidence, which is dishonest. Both attitudes are, shall we say, less than ideal.
Of course, atheism is simply the operative example. You can believe in as many or as few gods as you like, you can follow whatever religion you happen to be convinced by, at the end of the day, if you cannot admit when those who don't believe it have a semi-decent point, even if you still disagree with the point, you are simply not being rational.
Of course, scripture does explain this common behavior. "And this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil." (John 3:19). As sinners, it's only natural for us to resist God to the bitter end. That's what sin is. We don't like doing the right thing, we even hate those who advise us on the right thing when we're doing the wrong thing. It takes great courage to rebuke a man, and even more to receive such a rebuke. Each and every one of us faces a choice: Do we love our sin so much that we follow it down to the depths of the second death, or do we love the God who first loved us? While there is breath in our lungs, there is still time to choose the latter. All it takes is the humility to recognise Jesus as Lord, believing He rose from the dead. If you're willing to listen to it, or even search for it yourself, there is sufficient evidence that this is the wise decision. But if you maintain the attitude that everyone is biased but yourself, you will never see anything that could be considered sense.