What are some ways that I can investigate the gospel further?
The most useful thing I did in this regard was to read the Gospels in the Bible for myself. Some of us have had some Biblical exposure as children, but usually this is rather haphazard. Get an easy-to-read modern translation and read Matthew, Mark, Luke or John. They don't take long to read. Then you are going right to the primary source so you are in an informed position to make your own conclusions.
A variant on this is to join in with a few others and investigate as a group. That allows you to ask questions, share insights and generally learn together. Many people have quietly asked themselves questions about the gospel so when they get together with some other enquirers it can be a very stimulating exchange. It has been a privilege of mine to have participated in many such groups.
There are also good books that you can read. I would be happy to suggest some if you contact me.