Luke wrote:
God knew what would be every single outcome of the creation he designed before he designed it.
Agreed. God did know man would sin and provided a Saviour for all men. God also knew who would believe and elected them.
God could have designed it in such a way as to avoid evil and suffering ever coming into being.
I disagree for two reasons. If man could not sin, man would be perfectly holy and equal to God. This cannot be. God cannot sin. Adam and Eve were good, but they had the ability to sin and did. Adam and Eve (or any created being such as angels) cannot be equal to God.
The second reason is love requires choice. In order to truly love someone you must have the choice and option of not loving them.
God has a purpose for everything he does.
Agreed, which refutes Unconditional Election. God must elect man for some reason.
Grace could not be displayed without evil.
Not so, God showed great grace and love to Adam and Eve. He created them good and without sin, he placed them in a magnificant garden and provided everything they would ever need to live.
Mercy could not be displayed without sinners who need it; sin was necessary for sinners to exist.
Well, strictly speaking, yes, mercy cannot be shown unless God provides forgiveness for sin. However, God did show love and kindness to man without sin.
Saying sin was necessary for sinners to exist is circular reasoning.
The cross is the central focus of the Bible and the most important event in the history of the universe.
Agreed, but you must include the resurrection with that.
Sin was necessary for Christ to die on the cross for sins.
Agreed, but a form of circular reasoning.
The cross was God's plan before he built the universe.
God could not create anything as perfect as himself. He cannot create himself. Anything he would create must be inferior to him. God cannot deny his love when he creates living beings, so must give them free will and choice. This free will must give a living being the choice to do good or evil. God knew that man would exercise his free will and sin and provided a Saviour for man.
The problem with Calvinism is that it puts God in a straightjacket saying God must perform a certain way. It allows no flexibility in God's actions or decisions. But man can and does adapt to changing situations, is man greater than God?
God did not create man to be evil, but God knowing man would do evil provided a way of salvation for man through his Son Jesus.
I have used the argument of our automobiles. Does Ford build cars that it knows can exceed known speed limits? Yes.
Does that make Ford Motor Company responsible when you get pulled over for driving 80 MPH on the highway? No.