Let's just note the contradiction in point 1.
First, it says that "God unchangeably ordained whatsoever comes to pass".
Then in the same breath, it says "yet neither is God th author of sin".
Just making these 2 claims don't make them both true.
The 2 statements are CONTRADICTORY.
If God ordains "whatever comes to pass" that would INCLUDE sin, since sin did come to pass.
Whoever ordains a plan IS the author of that plan.
I'll give you an example from Scripture.
The murder of Uriah the Hittite. Who murdered him?
a. army of Rabbah
b. Joab
c. David
God held David guilty of murder of Uriah. Yet, David never laid a hand on him. But it was David who ORDAINED the plan to have Uriah killed.
So, WHOEVER ordains an action, IS the author of that action.
So, the WCF is contradicted.
I have used that example of Scripture for years ... I have a bit more patience than you though. I wait until my opponent is neck deep in his argument, then bring that up.
You did present it well, showing the multiple layers between David and the army of Rabbah.
But if you don't mind, let me expound a bit.
In Calvinism, the argument of secondary causes is that the FINAL "free agent" is culpable for the offence. (Not the FIRST free agent that decreed the event.
In the story presented FROM SCRIPTURE the army of Rabbah killed Uriah the Hittite.
There were however four levels of free agents involved in Uriah's death.
1. The army of Rabbah.
2. The men of the Israelite army under Joab's command that knew this action was wrong, because it was a practice of war at that time to not to get too close to the walls because of hot oil, and or stones being dropped on them.
3. Joab. When Joab sent word to King David, we read the following:
11:20 And if so be that the king's wrath arise, and he say unto thee, Wherefore approached ye so nigh unto the city when ye did fight? knew ye not that they would shoot from the wall?11:21 Who smote Abimelech the son of Jerubbesheth? did not a woman cast a piece of a millstone upon him from the wall, that he died in Thebez? why went ye nigh the wall? then say thou, Thy servant Uriah the Hittite is dead also. 2 Samuel
Joab also knew this act was wrong.
4. David. David orchestrated this entire event, and God held him alone responsible.
But let's take this one step further:
The WCF states, "God unchangeably ordained whatsoever comes to pass" ... this means that there were actually five steps to the above story.
5. God. God ordained each of the above previous steps (according to Calvinism). Now since (according to Calvinism) only the FINAL free agent is culpable, why didn't God hold the army of Rabbah responsible for Uriah's death?
Why did God skip not only the FINAL free agent, but the second, and third to the final free agent. So God skipped three free agents, to pin the responsibility of Uriah's death on David, but stopped short of blaming Himself of what He Himself ordained (according to Calvinism).
Maybe one of our Calvinist here would like to answer that question.