The sin of unbelief. God will not force you to receive his gift, if you die having rejected his gift. then you will have died in the state of committing the unpardonable sin
13 who was before a blasphemer, and a persecutor, and injurious: but I obtained mercy, because I did it ignorantly in unbelief. 14 And the grace of our Lord was exceeding abundant with faith and love which is in Christ Jesus. 15 This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners; of whom I am chief.
Christ came into the world to save sinful unbelievers.