Strict Justice vs Pactum Justice

I've been considering afresh the relationship of pactum justice with respect to Adam in the CoW and how that relates to strict justice in redemption. With Adam the reward would've been disproportionate to the work. The justice would not have been according to strict justice but rather according to an agreement to over pay Adam, a pactum justice if you will. The value of the work would not have intrinsic value. No problem there I trust. 

I do find that in redemption our reward though received by grace alone is according to strict justice. The passive obedience part that deals with our demerit is more obvious perhaps, but I think some who focus on active obedience have no place to ground strict justice with respect to our right standing before God. Let me frame the dilemma and then try to solve it, but before that I'll try to address the easier part having to do with strict justice as it relates to our demerit. 

The one time sacrifice was sufficient payment to satisfy God’s strict  justice. The divine nature was required so that satisfaction could be actually intrinsic to the work. Our demerit needed the incarnate Son of God to pay for the sins of His people, for one thing to keep his human nature from sinking under God's infinite wrath. Christ being God could render God propitious and truly provide full satisfaction, a strict just payment for our sins. That's the more obvious part. No issues I trust.

The dilemma:

The Son assumed the terms of the covenant that offered a disproportionate reward for works done as a human being. So, regarding the active obedience part, I don’t see how pactum justice can be avoided and strict justice obtained if our positive merit is predicated solely on Christ fulfilling the original terms of the covenant and we grant that those original terms were according to pactum justice. I think that’s the necessary implication of a position that limits our positive standing to that which we receive only by the active obedience of Christ. If the Son took on the terms of the original covenant and if those terms offered disproportionate reward via pactum, then it stands to reason that our right standing is not according to strict justice. 

We should look at this from another angle:

Although the required work was essentially* (footnote) the same for both Adams and, therefore, disproportional to the reward, in our receiving of the whole person of Christ and not merely His obedience in the economy of redemption we do find strict justice. In other words, by union with Christ we are by grace rightful co-heirs to the heavenly Jerusalem etc. Not by His work only but by our union with the architect himself. I think if we want to speak of our reward of all things in Christ being strictly just, then I think we need to abandon the notion of merely obedient-merit imputed and start thinking in terms of Christ’s perfection being imputed in union. I fear this is eclipsed in certain quarters. Where do we ground strict justice if all Christ did for us was obey as the Second Adam in our stead as opposed to taking us into union with Himself? We have by grace what the Son has by nature and we receive that in union with Christ. I think some constructs that emphasize active obedience fail to do justice to the implications of union with the perfections of Christ – the whole Christ, which includes yet exceeds his work of obedience. There's not a strict parallel to Adam, nor is there one in Romans 5.

Footnote:

*Of course Christ had a harder task. Adam had to be obedient in a world with the serpent but not in world with human disciples of the serpent.