By special request, this week's heresy was mentioned on the YouTube live recording of Table Talk Radio show #239 (where I got 2,000 TTR points, by the way).
Molinism is a 16th century protestant Semi-Pelagian heresy (of a largely Calvinist bent) that attempts to reconcile predestined action and free will. Molina taught that God has three sets of knowledge, obtained by God in this order: necessary truths, “middle” knowledge (or counterfactuals) and free knowledge (the ontology of the world). They believe that God uses His “middle” knowledge and foreknowledge to survey all possibilities (somewhat like multiple realities) and then actualize whichever one He wants to come to pass. Essentially, it was used to try and explain that while we still have free will (we can and do choose whatever action we want in some realm of existence) that God still has final control to make His predetermined outcome ultimately occur. Molina believed that one could learn about salvation by understanding this concept. This attempt was made to try bringing Arminianism (free will) and Calvinism (predestination) into harmony.