Not once in all of scripture are we told to keep silent when error is preached. In fact, just the opposite is true.
Overall true, yet with exceptions as,
Then came his disciples, and said unto him, Knowest thou that the Pharisees were offended, after they heard this saying? But he answered and said, Every plant, which my heavenly Father hath not planted, shall be rooted up. Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch. (Matthew 15:12-14)
A very bad condition and warning. May we who have been planted by God cleave to the Lord with purpose of heart, and warn the lost of their error and end.