What is wrong with refugees and immigration?

First of all, these may sound like obvious questions, but I prefer to ask a person instead of reading about it. I'm asking so I can get a very clear understanding of conservative thinking, and not just refuse it based on my assumptions of what it is. Make the answers short and sweet. You don't have to include a source in the comment, but make sure that you are able to provide it if asked.

1. What is wrong with letting refugees in?

2. What is wrong with immigration?