This article by Dr. David Allen addresses the need for unlimited atonement, and the relationship between faith and freedom.
We do not believe that compatibilism comports with genuine freedom. The reason should be obvious. In this construct, God imposes regeneration, and the individual is “free” to exercise faith but he is not free to choose any differently. By any normal understanding of freedom, this is not freedom. In order to have freedom, there must be the opportunity for a genuine choice between at least two options, and there must be no coercion made with respect to the choice.