It is not "evident IN SOME WAY God's attitude toward us was changed." This is a major flaw in your premise. We KNOW assuredly that God's 'attitude' wasn't the main issue that needed changing, for in fact, God's attitude cannot change. For if God's attitude needs changing, then He is imperfect. His eternal hatred of sinners and of the sin they commit is incontrovertible and will be infinitely demonstrated at the final judgment when all those who are outside of Christ are cast into eternal torment.
If God's attitude does not "change" then how would you understand a verse such as this:
"And through Him to reconcile all to Him(making peace through the blood of His cross), through Him, whether those on the earth or those in the heavens." (Col 1:20)
Does this reconciliation and "making peace" have only to do with our attitude towards God or does it involve God's attitude toward believers also?
Or how about these two verses:
Psalm 103:9 He will not always chide, nor will he keep his anger forever.
Who is a God like you, pardoning iniquity
and passing over transgression
for the remnant of his inheritance?
He does not retain his anger forever,
because he delights in steadfast love.(Mic 7:18)
These verses seem to show a "change" in God's attitude from "Anger" to "not angry".
What you apparently do not grasp or perhaps reject is that the perfect sacrifice of the God-man was more than a simple offering. JUSTICE had to be done which demanded punishment; eternal punishment for sins committed against Almighty Jehovah. In fact, if any human being after Adam had lived a perfect life, they would still be liable for judgment for they are by nature and imputation, guilty before God. It took one who was inexorably holy, pure, undefiled... One who was the effulgence of God's own glory, to stand in the place of needy sinners. But again, this in itself could not satisfy the wrath of God, for the LAW had been broken and PUNISHMENT had to be exacted upon the guilty. And it was SIN that was the proximate cause and thus the transgression of the law needed to be paid for. God's wrath was poured out upon the incarnate Son of God and Christ suffered that eternal and infinite wrath and separation from God for His sheep. It was THEN, after the punishment had been received that God was satisfied. The resurrection was the justification of Christ in that it testified to His moral perfection, thus showing He Himself needed not to bring a sin offering for He was not guilty according to law.
God CANNOT simply forgive anyone, not even Christ, just because an offering brought before Him is perfect. JUSTICE must be done. The spotless Lamb of God was the only acceptable offering and worthy to receive the just punishment due in regard to sin, for "Him who knew no sin he made to be sin on our behalf
; that we might become the righteousness of God in him." (2Cor 5:21)
So, is it you are not knowledgeable of what is required of the law of God and of God's infinite holiness? Or, are you in fact quite aware of these things but you chose to reject these truths?
I don't want to reject anything that is true. Why not provide a few verses that speak about Jesus Christ suffering the wrath of God or being punished and we'll discuss.