You are assuming that God changed from the God of the old testament to a different God with different ways in the new testament. That is not fact at all. God forgave sins in the old testament, God forgives sins in the new testament, it is the same God. The saints were preserved in sleep in the old testament, after Christ the saints were preserved in life.
If you truly believed that God changed between testaments, please give scripture telling us there is a new God. In the gospels it states that Christ changed nothing of his father.
“And if ye shall despise my statutes, or if your soul abhor my judgments,
so that ye will not do all my commandments, but that
ye break my covenant:
I also will do this unto you; I will even appoint over you terror, consumption, and the burning ague, that shall consume the eyes, and cause sorrow of heart:
and ye shall sow your seed in vain, for
your enemies shall eat it. And I will set my face against you, and ye shall be slain before your enemies: they that hate you shall reign over you; and ye shall flee when none pursueth you.
And
if ye will not yet for all this hearken unto me, then I will punish you seven times more for your sins. And I will break the pride of your power; and I will make your heaven as iron, and your earth as brass: And your strength shall be spent in vain: for your land shall not yield her increase, neither shall the trees of the land yield their fruits.
And
if ye walk contrary unto me, and will not hearken unto me; I will bring seven times more plagues upon you according to your sins. I will also send wild beasts among you, which shall rob you of your children, and destroy your cattle, and make you few in number; and your high ways shall be desolate.
And if ye will not be reformed by me by these things,
but will walk contrary unto me; Then will I also walk contrary unto you, and will punish you yet seven times for your sins. And I will bring a sword upon you, that shall avenge the quarrel of my covenant:
and when ye are gathered together within your cities,
I will send the pestilence among you; and ye shall be delivered into the hand of the enemy.”
Leviticus 26:15-25 KJV
your right that God hasn’t changed but you are missing this part over the law
“
Behold, I send an Angel before thee, to keep thee in the way, and to bring thee into the place which I have prepared. Beware of him, and obey his voice, provoke him not; for he will not pardon your transgressions: for my name is in him.”
Exodus 23:20-21 KJV
when you are thinking he forgave sins under the law consider who this is here bearing the lords title
“And while the children of Israel were in the wilderness,
they found a man that gathered sticks upon the sabbath day.
And they that found him
gathering sticks brought him unto Moses and Aaron, and unto all the congregation.
And
the Lord said unto Moses, The man shall be surely put to death: all the congregation shall stone him with stones without the camp.
And all the congregation brought him without the camp, and
stoned him with stones, and he died; as the Lord commanded Moses.”
Numbers 15:32-33, 35-36 KJV
I agree God has never changed
“And the scribes and Pharisees brought unto him a woman
taken in adultery; and when they had set her in the midst,
They say unto him, Master, this woman was
taken in adultery, in the very act. Now
Moses in the law commanded us, that such should be stoned: but
what sayest thou?
So when they continued asking him, he lifted up himself, and said unto them,
He that is without sin among you, let him first cast a stone at her.
And they
which heard it, being convicted by their own conscience, went out one by one, beginning at the eldest, even unto the last: and
Jesus was left alone, and the woman standing in the midst. When Jesus had lifted up himself, and saw none but the woman,
he said unto her, Woman, where are those thine accusers? hath no man condemned thee?
She said, No man, Lord. And Jesus said unto her,
Neither do I condemn thee: go, and sin no more.
Then spake Jesus again unto them, saying,
I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life.
The
Pharisees therefore said unto him, Thou bearest record of thyself; thy record is not true.”
John 8:3-5, 7, 9-13 KJV
it’s just a matter of who is God when he manifest himself in the world and who was set over the law
“Wherefore then serveth
the law? It was added because of transgressions,.. and it
was ordained by angels in the hand of a mediator.”
Galatians 3:19
Whe. They sacrificed animal blood for forgiveness it didn’t remit thier sins because they never repented it actually being done repetitively reminded them of their sins
“For the law having
a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect.
But
in those sacrifices there is a remembrance again made of sins every year.
For it is
not possible that the blood of bulls and of goats should take away sins.”
Hebrews 10:1, 3-4 KJV
it was a blueprint given to Moses of what would come in Christ