That is not true.
Not every party holds the unconditional support and defense of just one person, as a litmus test for membership. That is what the Republican Party has right now. Donald Trump is an especially petty and vindictive person. At the moment, the rest of the Republican Party is bending to Donald Trump's will and moving to expel anyone who failed to participate in Trump's scheme of retaining the presidency, even if that meant taking action in direct violation of their oaths of office and the United States Constitution, such as Georgia Governor Brian Kemp and the Georgia Secretary of State Brad Raffensperger.
The Republican Party was not a cult in 1974. Party leaders such as Tennessee's own Senator Howard Baker, asked tough questions of members of Richard Nixon's Administration during the Watergate hearings. They made sure the principal figures were held accountable. Had Richard Nixon not resigned, he would have been removed from office with a bi-partisan conviction in the United States Senate. No reprisals were ever taken against Sen. Howard Baker for his opposition to President Richard Nixon's misconduct, concerning the break-in at the Democratic Party headquarters of the Watergate Hotel in June of 1972, and the cover-up, authorized by Richard Nixon himself, that ensued.
The Republican Party desperately needs a Senator with the backbone of Howard Baker right now, and they do not have one. That is why the Republican Party is a cult.