They are important because many Christians do not know how to properly convey the Gospel. There are certain denominational prejudices or biases that have been in their denominations for decades, and they will naturally see their way as right. Unfortunately, they come across as judgemental and intollerant. While such people comprise a small percentage of Christiandom, most non-Christians deem them as the entirety of Christianity. The hurt that such an approach has caused has given rise to suicides and throwing kids out of houses, for example.
Every person has a background.
It could be anything. A family trajedy. It is very important to take this into account, and not to react towards the person. There may be more than meets the eye. Some questions go way beyond us.