Evangelizing means lecturing on how your religion or your sect just has to be true. There are any number of different evangelists giving different messages and most people are bored and tired of listening to them. They can't all be right can they?
Christian evangelists at first they try and tell you what they say is good news. Later if you're taken in by their message you end up paying more than you can afford to their church and obeying their rules, you never dare to think for yourself in case doubting will get you to Hell.
It is alleged that evangelists sometimes can cause psychological damage. "By breaking down self-confidence, self-esteem, a sense of one's ability to know what is right intuitively and trust one's own instincts. "- 
Sadly the harm evangelists can do doesn't stop them annoying other people preaching door to door, at street corners etc etc etc.
Evangelical is what they call people who are so religiously fanatic that they annoy, hurt, or even ruin the lives of others. It is a word commonly used with missionaries, or just very loud Christians. Evangelical can also mean a Protestant who doesn't necessarily evangelise in annoying ways.