Did Jesus die for the sins of the whole world, or only the sins of the elect? Did Jesus's death purchase a mere possibility for all, or was it absolutely effective for certain individuals? What does the Bible say?
For more information, see:
Canons of Dort, Second Head of Doctrine
Death of Death in the Death of Christ by John Owen
From Heaven He Came and Sought Her: Definite Atonement in Historical, Biblical, Theological, and Pastoral Perspective by Johnny Gibson
Redemption Accomplished and Applied by John Murray