Before we address the question directly, some preliminary observations would be helpful.
The Bible is very clear in affirming that God is a being of absolute goodness. The Psalmist declared: “Good and upright is Jehovah?” (Psalm 25:8; cf. Psalm 100:5). Whatever God does, therefore, is good—whether or not man can understand it (Isa. 55:8-9).
God is also just. Justice is one of the elements that lies at the very foundation of his sovereign rule (Psa. 89:14). The Judge of the earth always “does what is right” (Gen. 18:25). As finite beings with limited understanding, however, we are unable to appreciate fully this reality.
When Job went through his anguished ordeal, in moments of weakness, he thought that God occasionally deals unjustly with people. He charged that Jehovah is not always good; sometimes, the patriarch alleged, he mocks “at the calamity of the innocent” (9:23). Later, when confronted with the power and wisdom of the Creator (chapters 38-41), Job confessed that his uninformed accusations had obscured the true plan of the Almighty (42:2-3).
Those who spend eternity estranged from the presence of the Lord (cf. Mt. 25:41; 2 Thes. 1:7-9), will do so because that is what they deserve. The “wages” of sin is death (Rom. 6:23), and eternal “death” is separation from the good and gracious Maker of mankind (Rev. 20:14-15).
Those who have accepted the loving favor of God, by humbly submitting to his revealed will (regardless of the time period in which they have lived), will enjoy the bliss of eternal life, i.e., everlasting communion with the Lord. The guilt of sin is removed from the submissive sinner, by virtue of the atoning death of Jesus of Nazareth (Gal. 4:4; Heb. 9:15-17).
On the other hand, those who reject the offer of salvation will not enjoy the reward of heaven (cf. Heb. 2:1ff; cf. 5:8-9; 1 Pet. 4:17).
Let us now address the first part of our question. Will there be degrees of reward in heaven? We believe that both scripture and common sense answer affirmatively.
There is no evidence that the human spirit, as to its basic constitution, will be changed by the experience of death. If it is the case, therefore, that we are capable of different levels of satisfaction and enjoyment now, depending upon our capacity for such, it follows that such likely will be the case in the eternal order of things. This seems to be a logical inference. How could most modern Christians, with their limited range of experiences, possibly appreciate heaven to the same degree as someone like the apostle Paul, who suffered so much for his eternal crown (cf. 2 Cor. 11:24ff)?
The Scriptures, in many places, seem to imply varying levels of reward for the redeemed. Everyone in heaven will be supremely happy, but the capacity of some would appear to be greater – by virtue of their sacrifices and spiritual development.