You've probably met the person, so dogmatic, they won't consider that they may be wrong, and their certainty can be quite intimidating, and can sway you to think they must be right. The only problem with that is that you can then meet someone else who believes the complete opposite and find that they are just as convinced. When you have these opposing views held with equal certainty, how do you know who's right?
Sometimes atheists like to point this out to Christians - "There are people with other religious beliefs who hold them just as strongly as you - are you saying they're all wrong?!" Now, I don't know why atheists think they can use this against religious people and exempt themselves from the force they suppose it has! Why can't the theist say to the atheist "All these people believe in the existence of something transcendent, and they believe it just as strongly, if not more strongly than you believe in materialism. Are you saying they're all wrong?!"
The atheist would be right to dismiss such a silly argument coming from a theist, and likewise, a Christian is right to dismiss such a silly argument coming from an atheist. The fact that people believe something strongly doesn't mean that they can't be wrong and you can't be right.
The answer is forget about the bluster and look at the foundation and examine the facts.
Christianity is the only worldview that actually fits reality - reason, self-consciousness, morality, creation, science, history and personal experience cannot be adequately accounted for on any other worldview. People just cannot live consistently with any other worldview, whether religious or atheistic. Their worldview doesn't provide them with the foundation upon which reason, self-consciousness and morality can stand.
As well as the foundation there are also the facts - the facts of fulfilled prophecy and the resurrection of Christ, etc.
The Christian doesn't have to engage in a dual to see who can pound the table hardest or shout loudest. In the face of dogmatic opposition, the Christian can calmly say the person is wrong, and can show why.
