When studying the Bible, how do I know if a passage is written to me or just for my learning?
Ask to whom a passage is addressed. Scripture can be for our learning without speaking directly to us; for example, Peter's accusation that Israel killed the Christ was addressed to men of Israel, not to a modern congregation. Determine the original recipient, then distinguish instruction for that audience from truths meant for your learning.
Les teaches that the foundational question in Bible study is always, "To whom is this being addressed?" A passage may be for our learning without speaking directly to us. His example is Peter's sermon in chapter 3. Peter does not sound like a modern pastor pointing at a congregation and saying, "You killed the Christ"; rather, Peter addresses "ye men of Israel" and charges them with delivering up, denying, and killing the Prince of Life. The first word in verse 19 is "Repent," because they had rejected and murdered their Messiah. That message was directed to that national audience. Les also cautions that this distinction must never be used as an excuse for anti-Semitism. So the way to know whether a passage is written to you or only for your learning is to identify the original audience and setting, then apply what Scripture intends for the reader without misdirecting the original accusation or instruction.