Critics of the Bible like yourself often ask "Why the need for sacrifice at all? Can't God just forgive?"
From the beginning we see God, due to his nature, cannot tolerate wickedness without divine vengeance on that man or substitute. In Genesis 4:10 it says, "And he said, What hast thou done? the voice of thy brother's blood crieth unto me from the ground."
The main proposition being conveyed to us is that God has this inherent natural compulsion for vengeance, to punish the guilty and vindicate the righteous.
Exodus 34:7 - Keeping mercy for thousands, forgiving iniquity and transgression and sin, and that will by no means clear the guilty; visiting the iniquity of the fathers upon the children, and upon the children's children, unto the third and to the fourth generation.
People will ask why can't God just forgive and clear the guilty? Because in order for a man to be acquitted there must be a payment made for what he has done. Why? Because God has a nature that is distinct and governs his will. His will is not arbitrary. Thus we read in Habakkuk 1:13 - Thou art of purer eyes than to behold evil, and canst not look on iniquity: wherefore lookest thou upon them that deal treacherously, and holdest thy tongue when the wicked devoureth the man that is more righteous than he?
Take for example, a man named Jeff has murdered a member of your family. He's taken into custody and appears in court. The judge says "I wish to show mercy to Jeff and set him free, with no ransom or recompense even though I know he's guilty." You would be rightfully angry, because justice was not served. So why do you question God for doing that which you want and expect an earthly judge to do?
If a judge just arbitrarily forgave the criminal, would you say the judge is just? No. Of course not. By doing that he has besmirched the value of the man that he murdered.
Jesus Christs death is the ransom and recompense for our sins in order that God may be just when He declares us sinners righteous. So what's the reason why God can't just forgive? Because He has to be just when he justifies the wicked. There must be a payment made, because He will by no means clear the guilty.
God hates evil because of the purity of His eyes, because He is perfect, just and holy. Evil is something He hates within his nature. Thus if He wills to acquit man of his sins, payment must be made.
This is why Paul says in Romans 3:23 - For all have sinned, and come short of the glory of God;
24 Being justified freely by his grace through the redemption that is in Christ Jesus:
25 Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
26 To declare, I say, at this time his righteousness: that he might be just, and the justifier of him which believeth in Jesus.
Propitiation means a satisfaction of wrath.
Don't deny the gift of God which is eternal life through Jesus Christ our Lord. Now is the day of salvation. Believe on the Lord Jesus Christ today.