Theists: How can predetermined fate and free will coexist?

[SteveII]

@OP

Understanding the doctrine of Molinism (named after 16th Century Spanish Jesuit theologian Luis de Molina) is one way to answer your question:

from Wikipedia article on Molinism:

God's types of knowledge

Kenneth Keathley, author of Salvation and Sovereignty: A Molinist Approach, states that Molinists argue that God perfectly accomplishes His will in the lives of genuinely free creatures through the use of His omniscience.[1] After Luis de Molina, Molinists present God’s knowledge in a sequence of three logical moments. The first is God's knowledge of necessary truths or natural knowledge. These truths are independent of God's will and are non-contingent. This knowledge includes the full range of logical possibilities. Examples include statements like, "All bachelors are unmarried" or "X cannot be A and non-A at the same time, in the same way, at the same place" or "It is possible that X obtain". The second is called “middle knowledge” and it contains the range of possible things that would happen given certain circumstances. The third kind of knowledge is God's free knowledge. This type of knowledge consists of contingent truths that are dependent upon God's will; or truths that God brings about, that He does not have to bring about. Examples might include statements like "God created the earth" or something particular about this world which God has actualized. This is called God’s “free knowledge” and it contains the future or what will happen. In between God’s natural and free knowledge is His middle knowledge (or scientia media) by which God knows what His free creatures would do under any circumstance. These are truths that do not have to be true, but are true without God being the primary cause of them. "If you entered the ice cream shop, you would choose chocolate" is an example of a statement God knows via middle knowledge. This is very difficult for some to grasp.

further down the page...

Molinists believe that God has knowledge not only of necessary truths and contingent truths, but also of counterfactuals. (God's knowledge of counterfactuals is often referred to as his middle knowledge, although technically that term is more broad than simply the knowledge of counterfactuals.) A counterfactual is a statement of the form "if it were the case that P, it would be the case that Q". An example would be, "If Bob were in Tahiti he would freely choose to go swimming instead of sunbathing." The Molinist claims that even if Bob is never in Tahiti, God can still know whether Bob would go swimming or sunbathing. The Molinist believes that God, using his middle knowledge and foreknowledge, surveyed all possible worlds and then actualized a particular one. God's middle knowledge of counterfactuals would play an integral part in this "choosing" of a particular world.
Molinists say the logical ordering of events for creation would be as follows:

1. God's natural knowledge of necessary truths.
2. God's middle knowledge, (including counterfactuals).
---Creation of the World---
3. God's free knowledge (the actual ontology of the world).

Hence, God's middle knowledge plays an important role in the actualization of the world. In fact, it seems as if God's middle knowledge of counterfactuals plays a more immediate role in perception than God's foreknowledge. William Lane Craig points out that “without middle knowledge, God would find himself, so to speak, with knowledge of the future but without any logical prior planning of the future.”[4] The placing of God's middle knowledge between God's knowledge of necessary truths and God's creative decree is crucial. For if God's middle knowledge was after His decree of creation, then God would be actively causing what various creatures would do in various circumstances and thereby destroying libertarian freedom. But by placing middle knowledge (and thereby counterfactuals) before the creation decree God allows for freedom in the libertarian sense. The placing of middle knowledge logically after necessary truths, but before the creation decree also gives God the possibility to survey possible worlds and decide which world to actualize.[5]