Complex sentence: They treated the whole of general relativity as absolute fact and aggressively attacked anything that could contradict it or create even the smallest doubt, ultimately to the point of ridiculing and attacking and sidelining the very idea of an FTL physics.
Split into simpler sentences: They treated the whole of general relativity as absolute fact and aggressively attacked anything that could contradict it or create even the smallest of doubts. Ultimately this even came to the point of ridiculing and attacking and sidelining the very idea of an FTL physics.