The opposition reductively believes this is an existential battle between “good and evil”, they’re the “good”, and that’s a position from which one can justify almost anything to eradicate “evil”.
Even many in the opposition agrees with many of his goals (control immigration, protect American industries, shrink the government).
You cannot have constructive dialog about astronomy with someone who thinks the sky is made of green and purple polkadots because that's what someone told them, and dismiss all evidence to the contrary as a massive conspiracy.
They don't even believe in democracy or constitutional rights - at least, for anyone but them.