fatal errors

“The first of Julian’s crusades added two Turkish laurels on his brow; and in the public distress the fatal errors of Warna were forgotten.”

The History of the Decline and Fall of the Roman Empire

“If then God hath not provided an infallible guide and judge in matters of faith, there is some other way whereby men may be secured against dangerous and damnable errors in religion, and whereby they may discern truth from imposture, and what doctrines are from God, and what not; and this our Saviour declares to us here in the text, namely, that an honest and sincere mind, and a hearty desire to do the will of God, is the best preservative against fatal errors and mistakes in matters of religion; ea'n tis the'le poiein.”

The Works of Dr. John Tillotson, Late Archbishop of Canterbury. Vol. 05.