If you make an altar of stones for me, do not build it with dressed stones, for you will defile it if you use a tool on it. Ex 20:25
Seems a bit random. Some say it is about not carving rocks like the pagans do, others say it makes the alter easier to tear down if it is defiled.
Peter talks about Jesus as the Precious Stone, and that you also, like living stones, are being built into a spiritual house to be a holy priesthood, offering spiritual sacrifices acceptable to God through Jesus Christ. 1 Pet 2:5
So bringing these two pictures together: We are like the stones of an altar and God wants us not to try and clean and dress ourselves up before joining His service.
In fact, the dressed stones are for pagan altars, to practice idolatry. These dressed stones have been worked on, to make them acceptable for the pagan god. In much the same way, to try and clean ourselves up to become acceptable to God is idolatry too. Do we really think that we can make ourselves clean enough and straight enough to make God say “yes”? If we think that, we are crafting an idol out of ourselves. It is totally fake.
Doing nothing is not acceptable either. So what our duty?
To join in, as we are, and become part of a spiritual house. You know the rest, Peter said it already.
Put it in our terms.
We might think we cannot serve God because we are disqualified by our own rough shape and dirtiness. Yet this is the very truth that qualifies us, because such stones can be built into God’s altar. But stones that try put on a smooth appearance of holiness are in fact disqualified. Putting on any sort of act is despised by God, and dressed stones are discarded.
There was one bunch of people Jesus disliked the most: The pretenders. We could call them hypocrites or impostors. These are the dressed stones that try to form an altar for God in man’s design. But God is elsewhere, with the rough and dirty stones pulled straight out of the dirt. Their spiritual sacrifices are acceptable to God because they are through Jesus Christ.