Just because you can't vote yet, doesn't mean you aren't going to have an opinion on issues around you. A lot of teens call themselves Democrats or Republicans long before they are old enough to register with a party.
With all the daily worries that accompany being a teen, it can seem hard to make space in your life to think about an issue that doesn't directly affect you. But doing so can help you feel a part of a community. It will also prepare you in case the time ever does come when that issue might be your very own.