Hindsight is 20/20, and we don't realize how reasonable the Biblical arguments were that the false teachers made were at that time.
Old Testament Scriptures and New Testament Prophecies.
The false teachers used the Old Testament Scriptures to support their false teachings. There are plenty of OT verses that talk about how Israel was God's chosen, and how they were the light of the world. If that was God's plan, then who can change it? I write about the "cornerstone" written about in Isaiah, how the false teachers used it and how Paul responds to it in Titus. I also write about the use of Scripture in Isaiah that the false teachers used to pronounce God's wrath on the Gentiles. Paul responds to it in 1 Thessalonians.
This should make us think differently when Paul quotes Old Testament passages. Is he simply quoting them to support his case, or is he quoting them in order to correct the interpretation of them by the false teachers. Check out the video below where I discuss further.
The false teachers also used prophecies spoken by true prophets in the Church at that time. I write about how Paul corrects their interpretations of those prophecies in Ephesians.
If you think the false teachers were just bumbling idiots then you don't understand what their false teachings were, which may have an impact on how you understand the correct teachings of the Bible. Mirror-Reading can help with that. The false teachers were trying to integrate Christ into their existing religious paradigms and their false teachings were the result of their attempts.