Complex sentence: Some of the ministers had heard that Hutchinson considered them to be unable ministers of the New Testament, and in private she essentially agreed that this was her opinion, and that she thought only Cotton preached with the "seal of the Spirit".
Split into simpler sentences: Some of the ministers had heard that Hutchinson considered them to be unable ministers of the New Testament. In private she essentially agreed that this was her opinion, and that she thought only Cotton preached with the "seal of the Spirit".