Picking up on the idea of morality's relationship to free will, we might look at one of Sartre's plays. In The Flies, Sartre argues through his characters that guilt is a choice - a choice of perspective.
The atheist Sartre, however, transforms these plays of fatality into a drama of choice that negates Judeo-Christian beliefs.
In a twist on the ancient/traditional story of the murder of Clytemnestra, Sartre presents her children as vindicators, not criminals. Orestes and Electra are punished by the Furies in the Greek versions of the story because they commit matricide while revenging their father's death.
In Sartre's version, Orestes ultimately is accosted by the Furies but closes his eyes to them and chooses to see his actions as just and therefore not subject to the punishment of these avatars of guilt, the Furies.
Morality then depends upon a point of view.
Kant does actually argue that we all have free will. If we did not have free will, he says, then none of our actions could have any moral content.
Kant argues that actions can only be moral or immoral if people have control over them. Since people's actions do have moral content, Kant argues, then we must necessarily have free will at least in some situations.
The concept of free will or determination is a challenging one in the literature to address. I think that it requires adopting an understanding of the dimensions of each side and the specific thinkers' positions on the topic. The fundamental issue in understanding the issue of freedom or determination comes down to the presence of a transcendental or totalizing figure. For Kant, there are some totalizing elements that indicate that while individuals have freedom, the use of such freedom is limited within a reasonable understanding of divinity and universality. Kant's vision of freedom is constructed so that all freedom is seen as a form of universal imperatives so that individuals see their actions in this scope. For Sartre, there is no totality and to think so is an exercise in "bad faith." There is little in way of determination in Sartre's conception, but rather only the concept of choice and freedom. Unlike Kant, Sartre sees consciousness as a pure exercise in freedom and complete autonomy. There is only agonizing conceptions of choice in Sartre's vision of consciousness.