There has always been false teaching, such as Satan’s lie in the garden, the antediluvian apostasy, the false teachings of Balaam, the false prophets that appeared in ancient Israel, and in the New Testament era there where the Judaizes, the Gnostics and so on.
What is unique in our day is the preponderance of false teaching. In the past, there were a few issues that would capture the hearts of the people, but today every teaching from the beginning of time until today is available at the touch of a button.
Now the Spirit speaketh expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils” – 1 Timothy 4:1
“Be not carried about with divers and strange doctrines” – Hebrews 13:9