There's an election on. That means (inevitably) there is a meme going around that says:
"Not voting is not a statement."
"It is rendering yourself invisible."
"It is silencing your own voice."
"It is allowing your future to be determined by other people and pretending that's a victory."
Change the words in the first line from "Not voting" to "Voting for something you don't believe in or for election promises you don't well understand" and I think you get closer to the truth:
Voting for something you don't believe in or don't understand is not a statement.
It is rendering yourself invisible.
It is silencing your own voice.
It is allowing your future to be determined by other people and pretending that's a victory.
If someone actually informs themselves about their options and thinks the best choice offered is none of the above then trying to shame them into voting for one of the choices they've informed themselves about and learned isn't for them does not improve the system. You're blaming the failure to represent all people on the people it fails to represent rather than the lack of representation.
Inform yourself about your choices in the election: what each party is promising, what those promises mean, how each candidate (and party) would actually fulfil their promises, and what fulfilled promises would really look like. This step alone makes you a much more committed participant than most of the people who vote.
If you find no one is promising what you believe in, you can call, email, or talk to them and tell them what's important to you and ask if they'll support it. But if none of them will represent you, don't let them off the hook by giving them your vote anyway. That's far more corrosive to democracy than staying home when no one could make it worth your while to go to the polls.
There is lots you can do to participate in democracy that's not voting. Push for change outside of the election by trying to convince your fellow voters of your view in the hopes that next time your choice will be on the ballot. Between elections is when almost all of the most important work regarding policy change in elections happens, and it's when almost no one actively participates.
Be kind to those who don't agree with you this election season. We've had enough of the other stuff.