Are there rules and regulations in the Old Testament? Yes, but God gave those rules and regulations to the Jews to protect them and to remind them of His covenant with them, not for any mysterious reasons. The Jewish holidays are feast days, not days of suffering.
There is one thing the Jews did that was grisly. They sacrificed the blood of innumerable animals to God (For the most part, they ate the meat.). Those sacrifices foretold the sacrifice that God’s Son would make on the cross for our sins.
He lived a perfect life, yet he died in immense pain. Beaten. Lashed. Shamed. Hung by nails on a tree. Every drop of blood drained from His body. He took our sins upon Himself. Because of our sins, He experienced separation from His Father. Because of His perfect life and perfect sacrifice, He returned to heaven and now serves as our High Priest. Even now He intercedes on our behalf with the Father (Hebrews 7:25).
But we make things too complicated. This is God’s universe. We are just here for God’s glory, but our egos demand that we do something. Like little children, we see mommy at the stove, and we want to cook too. Yet our Father knows we don’t know how to cook. The Bible tells His story, but we don’t understand what Jesus did. God knows that if we enjoy, praise, and are thankful for what He cooks we have done all we can do.
The teachings of the Pharisees infuriated Jesus. Why? What angered Him? For the sake of their own glory, the Pharisees had added the commandments of men, arcane rules and regulations, to the Bible.
Consider what the Pharisees did with the Sabbath. The Sabbath was suppose to be a day of rest, a day off to give everyone time to be with family, friends and God. The Pharisees turned that into a day it was not even permissible for God to heal the sick. How stupid is that?
Matthew 12:9-14 New King James Version (NKJV)
Healing on the Sabbath
9 Now when He had departed from there, He went into their synagogue. 10 And behold, there was a man who had a withered hand. And they asked Him, saying, “Is it lawful to heal on the Sabbath?”—that they might accuse Him.
11 Then He said to them, “What man is there among you who has one sheep, and if it falls into a pit on the Sabbath, will not lay hold of it and lift it out? 12 Of how much more value then is a man than a sheep? Therefore it is lawful to do good on the Sabbath.” 13 Then He said to the man, “Stretch out your hand.” And he stretched it out, and it was restored as whole as the other. 14 Then the Pharisees went out and plotted against Him, how they might destroy Him.
How stupid and hateful can we be? God knows, and so He came to save us.