What is the difference between Arminianism, Molinism, and Calvinism?

TL;DR: Calvinists and Arminians disagree about whether man is able and/or free to choose God, Molinism is to do with God's knowledge and not salvation, so can fit with either.

Molinist here - Molinism isn't technically a view of soteriology (meaning to do with man's salvation), but is a view of God's knowledge, summed up pretty well by the gotquestions article referenced by Lesley. Molinism's two main points (or core doctrines) are:

1: God has Middle knowledge

2: Man, at least some of the time, has libertarian free will (although the precise definition is disputed, a reasonable interpretation of the term is 'the ability to do otherwise')

Arminianism and Calvinism, on the other hand, are directly opposing views that are to do with soteriology, not God's knowledge. Thus, you could be an Arminian Molinist or a Calvinist Molinist. The latter, however, is quite rare.

Calvinism is a very difficult doctrine to clearly define, but a working minimum of the system is summed up by the acronym TULIP. I won't go into a lengthy description of each of the letters (it's well documented in many places) but in summary Calvinism teaches that man, in his natural state, is completely unable to come to God (T) . God then 'elects' certain individuals whom He decides to save (U) and draws them to himself via irresistible grace (I) (literally irresistible, the elect person is unable to reject or refuse the grace). Additionally, Christ's atonement only covers and was only intended for these elect (L), and finally, the elect will never fall away or apostasize (P).

Arminianism is even harder to specifically define, but the gist is that although man would be unable to come to God alone, God's grace (prevenient grace) overcomes this state and enables all men to come to God and be saved, although it doesn't guarantee any will or force anyone. Christ's atonement covers any and all who come to Him, and is not limited. Beyond that, there are a lot of variations of Arminianism that I don't know as much as I should about.

It is worth noting that some (Many? Most?) Molinists hold to a soteriology which is similar to Arminianism but goes further in regards to God's providence and the election of individuals while maintaining free will, but that is beyond the scope of the question as it technically isn't Molinism proper.

Hope that helps 🙂

Extract from William Lane Craig answering a question on the complexity of Molinism :

Actually, I have no problem with certain classic statements of the Reformed view. For example, the Westminster Confession (Sect. III) declares that

God from all eternity did by the most wise and holy counsel of his own will, freely and unchangeably ordain whatsoever comes to pass; yet so as thereby neither is God the author of sin; nor is violence offered to the will of creatures, nor is the liberty or contingency of second causes taken away, but rather established.

Now this is precisely what the Molinist believes! The Confession affirms God’s preordination of everything that comes to pass as well as the liberty and contingency of the creaturely will, so that God is not the author of sin. It is a tragedy that in rejecting middle knowledge Reformed divines have cut themselves off from the most perspicuous explanation of the coherence of this wonderful confession.

William Lane Craig is Research Professor of Philosophy at Talbot School of Theology and Professor of Philosophy at Houston Baptist University.

The whole article is on Reasonable Faith .org

(I do not personally subscribe to these arguments and proposals. I simply report the existence of the references and statements.)

I found an article that explains Molinism in simple, easy to understand language. The second part of the article asks whether it is biblical, but I have left that part out since this is not what you ask. Here is a partial quote:

Molinism is named for the 16th-century Jesuit, Luis de Molina. Molinism is a system of thought that seeks to reconcile the sovereignty of God and the free will of man. The heart of Molinism is the principle that God is completely sovereign and man is also free in a libertarian sense. Molinism partly seeks to avoid so-called “theological determinism”: the view that God decrees who will be saved or damned without any meaningful impact of their own free choice. Today’s highest-profile defenders of Molinism are William Lane Craig and Alvin Plantinga.

The primary distinctive of Molinism is the affirmation that God has middle knowledge (scientia media). Molinism holds that God’s knowledge consists of three logical moments. These “moments” of knowledge are not to be thought of as chronological; rather, they are to be understood as “logical.” In other words, one moment does not come before another moment in time; instead, one moment is logically prior to the other moments. The Molinist differentiates between three different moments of knowledge which are respectively called natural knowledge, middle knowledge and free knowledge.

1. Natural Knowledge – This is God’s knowledge of all necessary and all possible truths: all things which “can be.” In this “moment” God knows every possible combination of causes and effects. He also knows all the truths of logic and all moral truths. This knowledge is independent of God’s will, a point few if any theologians would dispute.

2. Middle Knowledge – This is God’s knowledge of what a free creature would do in any given circumstance. This knowledge consists of what philosophers call counterfactuals of creaturely freedom. These are facts about what any creature with a free will would freely do in any circumstance in which it could be placed. This knowledge, like natural knowledge, is independent of God’s will.

3. Creative Command – this is the “moment” where God actually acts. Between His knowledge of all that is or could be, and all that actually comes to be, is God’s purposeful intervention and creation.

4. Free Knowledge – This is God’s knowledge of what He decided to create: all things that “actually are.” God’s free knowledge is His knowledge of the actual world as it is. This knowledge is completely dependent on God’s will.

Using middle knowledge, Molinism attempts to show that all of God’s knowledge is self-contained, but it is ordered so as to allow for the possibility of man’s free will. In other words, man is completely free, but God is also completely sovereign—He is absolutely in control of all that happens, and yet humanity’s choices are not coerced.

According to Molinism, God omnisciently knows what you would have been like had you lived in Africa instead of Australia, or had a car accident that paralyzed you at age 9. He knows how the world would have been changed had John F. Kennedy not been assassinated. More importantly, He knows who would choose to be saved and who would not, in each of those varying circumstances.

Accordingly, it is out of this (middle) knowledge that God chooses to create. God has middle knowledge of all feasible worlds, and He chooses to create the world that corresponds to His ultimate desires. Therefore, while a person is truly free, God is truly in control of who is or is not saved. Molinists differ on how God defines His underlying desires. For example, some believe God is seeking the maximum number of people to be saved. Others believe God creates in order to maximize some other divine goal. Source: https://www.gotquestions.org/molinism.html

As to how it differs from Arminianism and Calvinism, I doubt I could do justice to that. Perhaps you could draw from these articles:

https://www.gotquestions.org/arminianism.html

https://www.gotquestions.org/calvinism.html

https://www.gotquestions.org/Calvinism-vs-Arminianism.html

Like Nigel J, I am simply presenting one particular point of view in the hope it will help to answer your question. I have permission to copy and paste the Got Questions article on Molinism.