Numbers 19 is about the laws of purification after contact with a dead body. The cleansing ritual includes sprinkling water mixed with the ashes of a red heifer.
Anything that comes in contact with a dead person is unclean. If they died in your tent, then your tent is unclean and also any open container is considered unclean.
Now, with our modern knowledge of germs, we can understand how you’d want someone who came in contact with a dead person to wash and wait a week before reentering the camp. And the part about open containers being unclean makes more sense.
But God doesn’t teach them about germs. He doesn’t teach them to use soap and warm water. He has them perform a ritual. The ashes of the sin offering, mixed with water, make the places and people clean.
How? It’s not science. It’s faith. Humans make things unclean. God makes things clean. God makes things new. God restores. God brings life where there was death.
The ritual isn’t what makes them clean. No Christian ritual makes you clean, forgiven, saved. It’s faith that does those things. It’s God, not the ritual that accomplishes anything.
You can’t “repeat after me” and say the magic words and get saved. You can’t raise your hand, or go forward, or take communion, or whatever other rituals there are and get saved by the action or the words. God saves you by your faith. The actions are a response to faith, hopefully.
Doing any of those things because you were supposed to doesn’t save you. Doing any of those things because you are afraid of hell and wanted “fire insurance” doesn’t save you. We are saved by faith in the God who saves by giving us the righteousness of Christ.
These laws about touching the dead person making you unclean makes me think of how Jesus took Jairus’ daughter by the hand before He told her to get up. He didn’t make Himself unclean. He told the weeping crowd that she was only asleep.
The one we might see as dead and gone and hopeless, He sees as just someone who needs waking up.