The Godhead being one in purpose.
 

There are various scriptural accounts of the Father and the Son seemingly not being in agreement. For example:

Here, the Father wants to destroy a wicked person, wanting to rid the earth of his influence. But the Son pleads for mercy, wanting more time to work with this person.

Thus, the Father appears to be all about justice and the letter of the law, while the Son sees things differently, seeking mercy.

Are these concepts one and the same and I am just not seeing it?

good cop, bad cop, but both cops have the same purpose.

For me, "purpose" doesn't quite capture their oneness.

There's a sociality, a lifting of all three through coordinated effort, that goes beyond "purpose."

Alma 34:15 And thus he shall bring salvation to all those who
shall believe on his name; this being the intent of this last
sacrifice, to bring about the bowels of mercy, which overpowereth
justice, and bringeth about means unto men that they may have
faith unto repentance.


Doctrine and Covenants 45:3 Listen to him who is the advocate
with the Father, who is pleading your cause before him--

Doctrine and Covenants 45:4 Saying: Father, behold the sufferings
and death of him who did no sin, in whom thou wast well pleased;
behold the blood of thy Son which was shed, the blood of him whom
thou gavest that thyself might be glorified;

Doctrine and Covenants 45:5 Wherefore, Father, spare these my
brethren that believe on my name, that they may come unto me and
have everlasting life.


Moses 7:39 And That which I have chosen hath pled before my face.
Wherefore, he suffereth for their sins; inasmuch as they will
repent in the day that my Chosen shall return unto me, and until
that day they shall be in torment;


These three passages combine to give me the following perspective on the atonement/plan of salvation:

--Christ came to the knowledge that man would be lost, since perfection was required for salvation and man would fall short of that.
--Christ formulated the plan that he would sacrifice and die for man
--Christ proposed his plan to the Father, pleading the case, and essentially causing mercy to overpower justice
--Father accepts Christ's plan


This is the same concept you outline in the passage from Luke.

Cornelius Plantinga's social trinitarian model?

It influences my thinking. I'm coming more from the side of process philosophy, though.

yuck :(

You really are alien. You don't like process philosophy, you don't like textual criticism and you don't like fiscal conservatism. How is it you function at all.

Correct me if I'm wrong, but I thought our doctrine is that it was the Father's plan and Christ fulfilled the role, rather than the other way around.

I don't worship a 30% God.