I agree with this.   The 1689 Confession begins with the statement that, 
The Holy Scripture is the only sufficient, certain and infallible rule of all saving knowledge and faith.  
@JonC does not agree with the 1689 Confession.
@JonC is not qualified to speak for Calvinists.  God was really taking our punishment Himself in the Person of Jesus Christ.
@JonC wants us to believe that 
"My God, My God, why have you forsaken Me?" Really means, "My God, My God, you haven't forsaken Me."  However, he is correct when he says that Christ was forsaken to suffer, particularly during the three hours of darkness.  Then, as we all know, the sun came out again, and our Lord could say, 
"It is finished," and it was.  The period of being forsaken was ended because God's justice had been satisfied, except for our Lord's death which followed almost immediately.
The Bible does indeed say that God forgives sins.  That is why God Himself, in the Person of Jesus Christ paid the penalty for our sins Himself, so that He might be 
'just and the justifier of the one who believes in Jesus.'
@JonC does not know the Bible.  To take just two verses, Romans 5:8-9.  
'But God demonstrates His own love towards us....'  How?  By forgiving our sins unilaterally?  No!  
'.... In that while we were yet sinners, Christ died for us.  Much more then, having now been justified....'  By what?  Simply by repentance?  No!  
'..... By His blood, we shall be saved from wrath through Him.' 
No, because God did not take some random bloke and make him a scapegoat, but came Himself (Acts 20:28) in the Person of the Lord Jesus to pay the punishment for our sins.
Yep!  Because the Bible says that is exactly what He did.  One person paying for the sins of another does not work in God's eyes because they are both sinners.  That is why it is said repeatedly of the Levitical sacrifices, that they must be 
'without blemish' (Lev. 1:3 etc.  Cf. 1 Peter 1:19)
Yes, that is why the New Covenant is described as being in Christ's blood  (Luke 22:20 etc.)
.  God must be 
'just and the justifier of the one who believes in Jesus.'
It means the same thing, as 
@JonC knows very well.
These are assumptions 
@JonC makes entirely without basis.  The Reformers, who were almost all 'Calvinists' (even before Calvin wrote a word) suffered and died for Biblical truth and against Romanism.
 The Bible treats sin as something 'metaphysical.'  
'And the LORD has laid on Him the iniquity of us all' (Isaiah 53:6).  
'And you know that He was manifested to take away our sins' (1 John 3:8)
God 'literally' forgives the sins of all whom He gave to Christ to save (John 6:39).
No one is made a new creation for whom Christ did not die (2 COr. 5:17).
'The LORD is well pleased for His righteousness' sake.  He will exalt the law and make it honourable' (Isaiah 42:21).  That was done by Christ upon the cross.
Amen.