Undoubtedly true

Ever notice that when someone uses the word "undoubtedly," what they really mean is, "I don't have evidence for this, so I'm claiming no one can doubt it, and I'm hoping you won't question it."

Same with words and phrases such as "everyone knows," "it's common knowledge," or "common sense tells us."

In history, the dictum is "no document, no history." Which means that if there's no document (used in the broader sense of the word) there's no historical veracity. You may have informed speculation, a reasoned guess, whatever -- but without the document, you have no history.

Even more so in the church. If you can't find the biblical, confessional, liturgical or patristic (preferably all 4) evidence for something you're teaching, don't teach it. You may be right. But give the matter some rest until you know for sure. Pray, study, read, ask your mentor, but above all, make sure there's evidence for what you're setting forth.

If it's a sermon, does the appointed pericope teach what you are wanting to teach? Or are you using the text as a jumping off point for a hobby horse you're currently riding?

Even better, just preach the text. God's word is there to bring His people into the kingdom. Let the word do the job it's there to do. You're a mouthpiece. That's all. It's not an exalted job title, but it's the one God gives you. Be honored to be what God has called you to be.