This sermon by Charles Spurgeon about the clean and unclean designations of the old testament was illuminating on the topic of the importance of being holy, separate, distinguished.
Read it here: The Clean and the Unclean
Below is an excerpt speaking of the Jews’ standard of separateness from the world and our separateness:
They would remain as much a distinct people, as if a great wall of brass had been built all around them, or as if they had been transported to some island, and an impassable gulf had been put between them and any other kindred upon earth. They were separated for ever. Now friends, you will say, “What is the use of this to us?” I answer, it is the earthly type of a heavenly mystery. When the Jews were put away as the people of God for a time, then the Gentiles were grafted into their olive, and though we did not inherit the ceremonies, we did inherit all the privileges to which those ceremonies point. Thus all of you who name the name of Christ and are truly what you profess to be, are solemnly bound to be for ever separated from the world. Not that you are to leave off your daily intercourse with men. Our Savior did not do so. He was holy, harmless, undefiled, and separate from sinners. Yet, you know, he was always in the company of sinners, sitting at their table, seeking their good, and hunting after their souls. He was with them, but he was never of them; he was among them, but always distinct and separate from them; not conforming himself to them, but transforming them to himself. He hath set us an example. It is not the seclusion of a hermit, nor the exclusion of yourselves in a monastery, where you would be of no service to your fellow-men, but it is a higher and more spiritual separation which I claim of Christians to-night. You are to be in the world, and among the world, you are to mingle with all sorts and conditions of men, but still to maintain the dignity of your newborn character, and to let men see that you are among them as a speckled bird, as a light in the midst of darkness, as salt scattered over putridity, as heavenly angels in the midst of fallen men. So are ye to be a distinct people, a chosen generation.
Just above this passage, Spurgeon made a very interesting point about the importance of ceremonial rituals. (Yes, interesting! Though I will admit I am reading Leviticus, the book of ceremonial laws, and it is not the most thrilling book of the Bible.) Among the Middle Eastern religions, the strict and stricter regulations of Muslims and Jews meant that there was little to no conversion between religions. Spurgeon says, “the familiarity which seems necessary in order to proselyte is quite prevented by the barrier that precludes from intercourse at the table.” I find that wording a little convoluted, but essentially, lifestyles and ‘customs’ are an important barrier to preserving your faith and preventing you from falling away. Humans have habits, and habits are powerful.
Leviticus 13 talks about infectious diseases and mildew (a spreading fungus) being “unclean.” This word unclean has the meaning of ceremonial uncleanness attached. In any case, it conveys the idea that an impurity spreads quickly. That explains a bit about how vigilant God wanted his people to be about staying holy and pure. The smallest dot can spread if unattended to. Intermarrying with surrounding nations resulted in increased the Israelites’ idolatry time after time. It is an important discipline to self-assess and to weed what needs to be got rid of. (This last little paragraph about Leviticus was from me, not Spurgeon. Take this last paragraph as me processing thought, not as a great preacher’s commentary.)