Say neither of us are French, have never been to Paris, and have never studied it. Everyone in France says one thing about the city Paris, but you say the opposite. I don't need to be an expert on France and Paris to say that the millions of people living there probably know better than you.
In the same vein, claiming you know more about a religion than the millions/billions of people who follow it is a low-IQ take, especially if the person making the claim knows nothing about the religion.
The person you are responding to is making a point that many Christians have made in the past and present. Hell, the entire story of Jesus in the Bible is one of conflict with existing religious and government institutions and authorities, culminating in his death at the hands of those same characters.
In the same vein, claiming you know more about a religion than the millions/billions of people who follow it is a low-IQ take, especially if the person making the claim knows nothing about the religion.