S: Sovereign Election
Both Molinism and moderate views of Calvinism seek to affirm both divine sovereignty and divine permission. God's permission means that He allows something other than Himself to exist. He gave humans the ability to choose, within certain parameters.
Some strict Calvinist argue that everything flows from a decree of God. The fall of humanity happened because God decreed it to happen. He did not allow it to happen. He was the ultimate cause of it. Most Calvinists (and most people in general) are repelled by that doctrine.
However, the moderate Calvinist faces logical problems within his theology. If God does not cause the fall or sin in our lives, but merely allows it, is His judgment of the sinner conditional - ie based on the condition of our sin. The sinner is damned by God in response to their sins. Calvin, himself, rejected this moderate form of Reformed theology because it abandons the classic view of God's sovereignty. It is very difficult to logically hold the idea that God sovereignly, unconditionally ordains all things, while saying that sinners are judged conditionally upon their sinful acts.
Molinsim would argue that God does sovereignly elect those whom He has chosen, by creating the world in which they would freely choose Him. William Lane Craig explains, "It is up to God whether we find ourselves in a world in which we are predestined, but it is up to us whether we are predestined in the world in which we find ourselves."
While Calvinism and Arminianism seem to ignore and interpret strangely portions of Scripture that do not line up with their theological system, Molinism allows for a robust view of both God's sovereignty and man's free will/responsibility. Scripture often focuses on the two side by side, yet the majority views in Christianity tend to elevate one and dismiss the other.
E: Eternal Life
Despite modern day ideas, historically, Calvinists have struggled with assurance of salvation almost as much Arminians. While an Arminian may worry that he will loose his salvation at some point in the future, a Calvinist may worry that he was never part of the elect and his experience is wrong.
According to Arminian theology, it is possible to forfeit your salvation. Calvin taught that God gives a temporary faith to some of the reprobate. That makes it seem to everyone, including that person, that they have been genuinely saved, but it is a false salvation given from God so that, according to Calvin's chosen successor Beza, "their fall might be more grievous." Some have said, and I agree, that seems dangerously close to divine sadism.
We can find our assurance only in Christ. The objective work of Christ is the only basis for assurance. Our works will not and cannot be the basis of our assurance. However, the works done by God through us can, and should, providing a supporting confirmation to the already present assurance. Scripture also teaches that true saving faith will endure until the end. The genuinely saved person will seek God. They may backslide for a time, but there can be no peaceful backsliders because if the Holy Spirit dwells in them, He will convict and discipline them.
S: Singular Redemption
The TULIP "L" is the most difficult to hold, both Scripturally and emotionally. Again, many Calvin scholars have said that Calvin did not hold to "limited atonement" himself. However, the Arminian view of "general atonement" has problems in that it does not secure salvation for anyone, but merely grants the opportunity.
The general atonement view of the Arminians says that redemption is obtained, salvation is obtained for all but secured for none. The Calvinist limited atonement view says that redemption is secured, salvation is secured for and only for the elect. The moderate and Molinist position says that redemption is provided, salvation is provided for all, but applied only to those who believe.
Holders of limited atonement are forced to conjure up weird explanations for Bible verses that clearly speak of Christ's death being for "all" and the "whole world." General atonement supporters have to be careful not to drift into universalism (everyone is saved because Jesus died for everyone) and argue that Jesus' death did not actually make Him our Savior, but rather open the door to the possibility of Him being Savior.
The idea of singular redemption says that Christ's death is universal in accessibility, but limited in application. Everyone can choose to access it, but only those who make the choice to follow Christ have the benefits of His death applied to their life.
OBJECTIONS
Molinism is just another form of Arminianism - said by a Calvinist. Molinism is just another form of Calvinism - said by an Arminian.
Any mediating position faces this criticism. Since it differs from one, it must be the other. This is a false dilemma and a bit condescending to imply that the only choices one has to explain the relationship between divine sovereignty and human responsibility are those two. It seems that both of those theological camps have been at war for so long, they see enemies in any person who will not whole-heartedly embrace every nuance of every position. Often times they engage in friendly fire within their own camp over minute differences. It is no real criticism to be attacked from both sides.
It is simply a philosophical concept. Why not just believe the Bible?
Yes, it is a philosophical concept. No, it is not simply a philosophical concept. Every way of looking at Scripture and trying to interpret them in a logical, coherent system is in some sense philosophy. You can simply say, "I believe the Bible." But so do Calvinist, Arminians, Molinists, Catholics, Baptists, Pentecostals, Orthodox, Methodists, etc. Even Jehovah's Witnesses and Mormons say they believe the Bible. It is not a matter of simply believing the Bible. To think deeply about the Bible, you have to explain how concepts like divine sovereignty and human free will interact.
How could God know the things that would happen?
Philosophically, this is called the grounding objection. At this point, Molinist would appeal to mystery.
Mystery is often mentioned by every side. Molinists would say that their appeal is the most satisfactory because it places the mystery within God's attributes, in this case his omniscience, whereas a Calvinist has to place mystery in God's character when he talks about the status of the unelect or in God's will when he speaks of why sin exists in the life of the believer. It is much more fulfilling to say that as a human being, I do not totally understand how God has all knowledge and that knowledge extends to things that would happen than to say I do not know if God really loves those He has not chosen to be elect.
CONCLUSION
If it is not obvious enough at this point, I would call myself a Molinist after a life of dissatisfaction with both the Calvinist and Arminian models and a time of studying and reading about other options. My position is one of humility in that Molinism seems to best explain all of the phenomenon, but I do not and cannot assert that it is the only way or that anyone who disagrees is somehow lacking in the biblical knowledge or relationship with Christ.
http://wardrobedoor.blogspot.com/2010/08/ring-around-roses-molinism-in-brief.html