The best definition of humility I ever heard was, "humility is agreeing with God". Humility, is not the same as humiliation, and is not the same as shame. It is not the same as letting someone walk all over you. When we believe in Christ and hold to a very narrow definition of salvation, God, heaven, hell etc, no doubt unbelievers will sometimes criticise us of being bigoted, proud, arrogant, stubborn. Even fellow Christians may accuse us of such. Particularly so called "liberal" christians. But because we agree with God, we are in fact very humble.
If someone is wrong, they are wrong, and I see no need to pretend to be wrong, if I know myself I am right, just to give an appearance of being humble. You try convincing me Jesus isn't the Son of God, I am not going to say, "well, that could be true, I've never thought of that before, thankyou for your input", I will say , no, Jesus is the Son of God, and you are simply wrong. Not from an attitude of pride and looking down upon someone, but as someone who is secure and grounded in the faith and who knows the truth. We can consider others better than ourselves, without having to compromise on our own beliefs or think that we are somehow wrong on matters of faith where there can be no doubt.