Both TDS and CTT exist, and we should not deny either
We should deal with policies, record, competence and character, not hatred of or devotion to (or fear of) President Trump.
The idealized, civics-class way of analyzing a political leader is by his character, policies and competence. But human beings are messy and flawed, so that is not how we deal with things as humans. We will always have biases, or we will see people differently based on external factors. Personality and loyalty, or personal animosity, can distort a logical analysis. But over the last decade, that has been especially pronounced with President Donald Trump.
We have two distinct errors, and people committing both errors point fingers at the other while denying their own bias. First is Trump Derangement Syndrome: Every single thing that Trump does is terrible, and even when he does things you like it was "by accident." The second is what Jonah Goldberg correctly labeled Critical Trump Theory. (TDS and CTT for short.) If you criticize Trump or disagree with him, you are a "Trump hater" and your argument can be dismissed. This is similar to people who make politically inconvenient arguments being called "racist" in order to dismiss the logical or factual merit of what they are saying.
We should guard against both. Conservatives (especially Christian conservatives) need to recognize the tendency to embrace CTT. It is a natural part of human nature to immediately be defensive of someone we support, especially someone who has been under constant attack for the last decade. It does not help that Trump is an extremely brittle man who consistently reacts in anger at even reasonable criticism. Many conservatives, fearful of his wrath, studiously avoid criticizing anything he does or says. Because many attacks are false, it is appropriate to speak in defense of the President, but we should consider whether Trump actually is wrong, and be willing to admit that error.
TDS is another matter. Even Trump's flaws and errors are often blown out of proportion, and Trump's critics would be wise to tone down their outrage in order to make their criticism more effective. I admit that, as a frequent critic of Trump, I have dabbled with TDS at times. It is important to recognize that both Trump Derangement Syndrome and Critical Trump Theory both exist and should be avoided. We should deal with policies, record, competence and character, not hatred of or devotion to (or fear of) President Trump.
I am eagerly anticipating January 20, 2029 when Trump is finally out of presidential politics and is back to being a private citizen. He will not go away and will still have a following, but the TDS/CTT distortion will (hopefully) be greatly lessened by then. The personality issues will always exist (we are flawed human beings after all) but Trump's influence heightens everything on both sides.