Good point.
We know that no single doctrine exists independent of its greater theology. The Synergist cannot believe in Definite Atonement because their greater theology prohibits it. If they were to believe in D.A. then their view of man having a self-autonomous free will collapses. This in itself is not a convincing argument for D.A., it is just an acknowledgement that the Synergist system is dependent on Universal Atonement. It is the only atonement view that allows man to retain his freedom of choice in salvation; i.e. "Synergism".
It works the other way around as well. The monergist is absolutely dependent on Limited Atonement. He must dismiss all Scripture that involves with free will, or redefine the terminology used such as he does in John 3:16. Everything must be interpreted in the light of a Limited Atonement or the entire TULIP collapses.
That is why the Calvinist has no good answer for Luke 23:33,34.
God simply wasted his time praying for those who were headed to eternal damnation asking for their forgiveness. What nonsense!
However, had they freewill they could of their own will rejected the offer which God foreknew they would (1Pet.1:2)
Here is another scripture to wrestle with:
Rom 9:1-3
(1) I say the truth in Christ, I lie not, my conscience also bearing me witness in the Holy Ghost,
(2) That I have great heaviness and continual sorrow in my heart.
(3) For I could wish that myself were accursed from Christ for my brethren, my kinsmen according to the flesh:
--Here Paul expresses a great love for the nation of Israel. In fact it is so great that he wishes he could trade places with them: his salvation for theirs. He is willing to be damned if the nation could be saved. How great love is this! It is incomprehensible.
Does Paul have greater love than God himself, who "is love"? That is almost a blasphemous question to ask.
And yet, looking at it from a Calvinist view point one would have to say "yes."
God only has love for a select few. For the rest there is no love. Just as "Esau have I hated," he has predestined for an eternity in the Lake of Fire. There never was any love for the non-elect.
But with Paul, his love is very great for the entire nation, most of whom are not the elect. The only answer to this enigma is the truth expressed in 1Tim.2:4,
1Ti 2:4 Who
will have all men to be saved, and to come unto the knowledge of the truth.
--It is not all kinds of people, but all people to be saved. That is his will that is expressed in this verse, and in many other verses throughout the scriptures.
Just as Paul had a love for all the nation of Israel to be saved,
so God has a love for all men to be saved.