A maximally great being cannot be both maximally just and maximally merciful for to express one trait is to diminish the other.
Thoughts?
I have heard people try and say that Jesus solves this but the idea of an innocent person being punished for the wicked does not seem like justice to me.
@zelph what you need to do before drawing these conclusions is define what you mean by maximally just and maximally merciful. If by maximal you mean perfect then I do not see how perfect justice and perfect mercy are incompatible. Let's keep it simple. Being just simply means
being fair and consistent with what is morally right therefore when we say God is just we mean He always acts and judges in a way that is fair and consistent with perfect moral standards. Being merciful simply means
being compassionate and forgiving. Your argument can be distilled to the proposition
a person that is fair and consistent with what is right is incapable of being compassionate and forgiving. Obviously this is not true and Jesus doesn't need to solve this "problem"; without Christ's atoning death, God still remains just and merciful.
Your argument is really embedded in your response to the assertion that Jesus fulfills God's demand for justice while at the same time showing mercy. Your assertion is that justice is not served when an innocent person is punished for someone else's sin. Is that really true? If I do something wrong but someone else is punished for it then you are right when you say that is not justice. But what if that person voluntarily chooses to take the punishment for me? Imagine you have been fined $100 million for a crime you committed and I have $100 billion cash in the bank. I see that you totally incapable of paying the fine and that you will live life as a slave to the courts working off that fine. Filled with compassion, I approach the courts and offer to pay your fine; afterall the $100 million is only 0.1% of my cash in the bank (It's proportionally equivalent to being asked to pay a fine of $1 when you have $1,000 in the bank). The courts demanded that the fine is paid and the fine is paid therefore justice has been served. If the courts had forced me to pay your fine then justice would not have been served.
This is similar to what Christ did. The just reward for our sin is a price we cannot pay for it means eternal damnation. God being just requires that this price is paid. However, God also being kind and compassionate taking pity on us sends Jesus,
who voluntarily agrees, to pay the price on our behalf. Being divine, Jesus is able to pay the price and therefore justice is served.