I have been Catholic my whole life and I listen to everything, including a lot of metal as well as other genres. I would say metal actually has a higher proportion of Christians and people who are following a basically Christian lifestyle (love thy neighbor, help your brother, marry your partner, care for your family) than other rock genres. A friend of mine who ran a small label, managed bands who played Wacken, and has a very popular radio show runs a massive food drive for charity every December, about the biggest one in his city, and has been doing this for years. Another guy is pro-Jesus to the point of offering Bibles on his merchandise table. So there is nothing inherently wrong with metal. A lot of it even has Christian messages. Some people get this and some don’t.
Most of the stuff about Odin, etc I can enjoy in the same way I enjoy reading old Greek and Norse mythology books; OK for entertainment but I’m not planning to start praying to Odin and Thor any time soon. If you taking it in that way, as entertainment and not a substitute for Jesus Christ, then no problem.
As I’m sure you know, there is also a subset of metal that contains lyrics that are on their surface anti-God, anti-Christian, or violent. This stuff has to be evaluated in view of the listener’s age, their level of involvement with the listening, and possible bad effects on them/their lifestyle, as well as whether there is blasphemy involved. Some bands and songs just go too far for me to feel comfortable and i dont support them. For the ones that could go either way, as middle-aged married person, I’m way past the age of being influenced by some song and I understand the context whereby some songs are not meant to be taken literally or are making some point about hypocrisy, national heritage etc but if it was some teenage relative of mine, I’d probably tell them not to listen.
When listening to any edgy music, be very careful who you get involved with because while there are many good people listening to it, there are also bad people who will lead you astray. We all know a few people who got a little too over involved and messed up their lives. And try to pick some metal with uplifting themes. I’m partial to Dio, Place of Skulls, Trouble and other doom bands myself, though there’s a lot more out there to choose from.
If at any time, you find that your listening habits are bothering your conscience or having a negative effect on your life, stop immediately. And if you’re still a minor, respect your parents’ wishes about your listening habits. If this is an issue, discuss it with them, but they have the final say until you are an adult living on your own.