the left deploys these evil ideas like “science”

There is legitimate honest it-really-exists propaganda put out by folks to the left of John McCain. PETA is a real thing. The Sierra Club is a real thing. The ACLU is a real thing. The DSA is real.

But the deck is stacked when you assert an advocated policy needs to be some kind of cosmological truth. I don't need "science" to tell me that Trans-people deserve equitable treatment or that shooting your 11-month old dog in a gravel pit is bad or that billionaires shouldn't exist. These are decidedly political views.

What's more, when I advocate for a position, I'm not going to argue "fairly" with a bigot, a dog-murderer, or a plutocrat. I'm going to make my strongest points and my hardest digs, then leave the opposition to make its own case. Given that I'm being outspent $1M:$1, I don't feel any need to develop a case for the TERF or a South Dakota governor or the megalomaniac profiting off lead paint sales on their behalf.

You don't need to be objective. You can have an opinion and still be a good leftist. You can even make a passionate, moving case that's intended to grip people on more than a purely logical level.

Don't let the right-wing asshats scare you away from showing your humanity when you're engaging in progressive politics.