Then maybe you should read the OT more. I don't mean plucking out a verse here and there....but follow the story line.
When things first fell apart in the Garden of Eden - how did God respond? Didn't HE - essentially suggest that He was the one that was going to resolve the problem when He said to the serpent:
"And I will put enmity between you & the woman, and between your offspring & hers; He will crush your head, and you will strike His heel" ~ Genesis 3:15
ISTM that you are creating a dilemma for yourself. Is the God of the OT a different God than in the NT? Did He change? Or - could it be that culture has changed and He - in His grace and mercy - is patient and is resolving things with His perfect timing?
King David (and other authors of the Psalms) recognized God's loving kindness and mercy when they wrote these passages:
Have mercy on me, O God, according to your unfailing love; according to your great compassion blot out my transgressions.
— Psalm 51:1
But you, Lord, are a compassionate and gracious God, slow to anger, abounding in love and faithfulness.
— Psalm 86:15
As a father has compassion on his children, so the Lord has compassion on those who fear him.
— Psalm 103:13
The Lord is gracious and righteous; our God is full of compassion.
— Psalm 116:5
The Lord is gracious and compassionate, slow to anger and rich in love. The Lord is good to all; he has compassion on all he has made.
— Psalm 145:8-9
And this one - Psalm 119:
"Blessed are they whose ways are blameless, who walk according to the law of the Lord. Blessed are they who keep his statutes and seek him with all their heart." v. 1-2
Let your compassion come to me that I may live, for your law is my delight.
— Psalm 119:77
So - did God's truth change from the time of the OT to the new? Or is truth and His nature eternal and unchanging?
What's meant here by "the law of the Lord" and "His statutes"...."law"?
Personally - I think this is something completely different than the Temple rituals. Those rituals & rules partially mimicked rituals of the Pagan culture (and what ancient Israelites kept going back to) but also were shadows of what Christ would carry out fully.
While King David was saying to God (through Nathan) that he desired to build God a suitable house (temple) - God seemed to only be appeasing David....and had other (better) plans.
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2 Samuel 7:4-8 ~
But that night the Lord spoke his word to Nathan, 5 “Go and tell my servant David, ‘This is what the Lord says: Will you build a house for me to live in? 6 From the time I brought the Israelites out of Egypt until now I have not lived in a house. I have been moving around all this time with a tent as my home. 7 As I have moved with the Israelites, I have never said to the tribes, whom I commanded to take care of my people Israel, “Why haven’t you built me a house of cedar?”’
8 “You must tell my servant David, ‘This is what the Lord All-Powerful says: I took you from the pasture and from tending the sheep and made you leader of my people Israel. 9 I have been with you everywhere you have gone and have defeated your enemies for you.
Which seems to go back to what was promised here, in Leviticus:
Leviticus 26:11-12 ~ I will live among you, and I will not despise you. 12 I will walk among you; I will be your God, and you will be my people.
And the key verses in 2 Samuel 7:
V 11 - 13 ~ Furthermore, the Lord declares that He will make a house for you—a dynasty of kings! 12 For when you die and are buried with your ancestors, I will raise up one of your descendants, your own offspring, and I will make his kingdom strong. 13 He is the one who will build a house—a temple—for my name. And I will secure his royal throne forever.