Phi 2:12 Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling. 2Pe 3:17 Ye therefore, beloved, seeing ye know these things before, beware lest ye also, being led away with the error of the wicked, fall from your own steadfastness.
Isa 8:20 To the law and to the testimony: if they speak not according to this word, it is because there is no light in them.
Mat 24:4 And Jesus answered and said unto them, Take heed that no man deceive you.
Mat 24:5 For many shall come in my name, saying, I am Christ; and shall deceive many.
Mat 24:11 And many false prophets shall rise, and shall deceive many.
Mat 24:24 For there shall arise false Christs, and false prophets, and shall show great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect.
Rom 16:18 For they that are such serve not our Lord Jesus Christ, but their own belly; and by good words and fair speeches deceive the hearts of the simple.
From the article: They also passed on and interpreted apostolic traditions that were not written down in the New Testament books, like the practice of meeting for weekly worship on Sunday, the day of the Lord’s Resurrection, rather than Saturday, which was the Jewish Sabbath. Finally, they were the ones responsible to authoritatively interpret and apply the sacred Scriptures amidst dispute and controversy, such as the fourth-century controversy over the divinity of Christ.
Mat 15:9 But in vain they do worship me, teaching for doctrines the commandments of men.
Jam 3:1 My brethren, be not many masters [teachers], knowing that we shall receive the greater condemnation.