The other day, I was questioned on whether I "actually am a leftist", by a friend. After I nervously answered fairly basic questions such as believing in healthcare and collective labor, they weren't convinced. Ever since that day, I felt like I couldn't be a leftist, especially since I lost any confidence in my ability to be "better" according to that person's standards. If I couldn't satisfy their standards that one time, what would be the point of trying to read theory and trying again? Yes I admit, I haven't tried to read theory. I have no confidence that I would do it correctly.

This is why you're supposed to join an org. Most serious orgs have an onboarding process where you'll be taught basic precepts and foundational texts of the ideology embraced by that particular org. You'll also be assigned to do work by the org, and be build up to become someone who embodies the ideals of the org. You have imposter syndrome because you haven't done anything to advance the emancipatory project, and you haven't done anything to advance the emancipatory project because you are not part of an org.

Unless you're some rich multimillionaire quietly funding underground Maoist insurgent cells, you'll not be able to contribute unless you're part of an org. If there are no suitable orgs near you, your responsibility is to either create your own org or support other orgs. Creating your own org is self-explanatory in a "draw the rest of the fucking owl" sense. Supporting other orgs can range from financially supporting them to doing agiprop for them. Even if you're the only leftist in a sea of Christofascists, you can still contribute to the cause. But you can't do this on your own. None of us can.