In some cases you can try to educate the relative, show them that your faith isn't what they think it is, the positives and how having that faith is helping you, and where their misunderstanding is based. It's always worth it to try, but also know when to walk away because you aren't going to change them.
If you have to walk away, I advise doing so completely. See and speak to them as little as possible, and make it very clear that while maybe you like them as a person and you understand their own faith you will not associate with them if they have a refusal to understand yours as well.
You're living with them I assume based on the wording of the question, and in that case there's even less you can do. If it's getting you in trouble then it's best to keep your faith hidden, even if that's hard. Fake being part of their faith if you must and if it'll keep you safe while you have to live with this person. If they refuse to learn and understand even after your attempts at education then honestly just move out as quickly as you can and cut them off - family is not blood, and you are not bound to them just because of it. If they're making your life miserable in any manner you have every right to walk away as soon as possible, letting them know why you are doing so and giving them a chance to realize what they've lost and get back into your life but also know when to cut off if they're not being genuine about it.
Do what you can but don't try to force it, hide if you must and trust in the understanding of who or whatever you worship to keep yourself safe, and if they won't understand get away as fast as possible and as completely as possible. You'll be much happier for it.
You don't get into verbal arguments with them and avoid situations that provoke these arguments as much as possible. There's no point arguing with someone that won't listen or doesn't have an open mind to things. That's the downside of being with religious folks but this isn't the case all the time, it's the case most of the time.
If there is one thing that is very common among human beings is the fact that we disagree on a good number of things. Living with someone who doesn't understand your faith or who has deliberately refused to hear anything about your faith can be very difficult. The only thing is to carry on with everything you do as your faith requires while also explaining the conflicting areas that he is not Ok with.
If he/she attends a church that is against your faith, then we might be dealing with a problem of denominationalism and not the faith. As christians, every dogma should be backed by the bible. So in every area where there is conflict, go back to the source and backbone of it all, the bible. In there are all the answers that you need. The truth is, most Christians just flow with everything that their Church says that they fail question if it is biblically backed.
I discovered a lot of things as biblically wrong that were accepted in my former Church only when I studied my bible and I saw that, what people have been saying as wrong was wrong actually but I always defended my Church without ever taking time to trace its biblical backing.
If he does not understand your faith, use your bible to make him/her understand by tracing the biblical backing for it and also show interest in listening to what he/she has to say about the areas in which he/she disagrees and the reasons which should be biblically backed too. You might be surprised when you actually give ear to what they have to say.
Most importantly, pray about it for God to give you a clear revelation of his word and more understanding. After all, it is because we all want to serve him in the right way that such disagreements arise in the first place. So always pray for his intervention and help.