Do not lay up for yourselves treasures on earth, where moth and rust destroy and where thieves break in and steal, but lay up for yourselves treasures in heaven, where neither moth nor rust destroys and where thieves do not break in and steal. For where your treasure is, there your heart will be also.Matt. 6:19-21
1. Since salvation is an entirely undeserved free gift not on the basis of our works but on the basis of God's election and the death, blood and resurrection of Jesus Christ, then how could it be that our heavenly reward is on the basis of our works?
2. What is this treasure in heaven? You see, I think there is a danger that since we think we have a pretty good idea what earthly treasures are we may carry that thinking over into what heavenly treasures are and liken them to worldly possessions, but since our greatest treasure is surely the Lord Himself, to be with Him, to see HIM face-to-face, to marvel and wonder and praise and prostrate and worship and adore and ... I'm not sure a concept of greater or lesser rewards fits with this image of a great throng of worshipping, glorified saints.
3 If our reward varies according to what we have done what would be the point of the parable of the workers in the vineyard (Matt. 20) who all got paid the same despite doing differing amounts of work?
On the other hand, hierarchical structures are everywhere in this world in politics, business and so on and clearly people receive differing gifts and abilities and seemingly differing degrees of grace from which it would seem reasonable to infer similar concepts in heaven, particularly when we consider that scripture does tell us about the special roles of the twenty-four elders and the 144,000 in Revelation. So, there could be varying rewards in heaven, albeit not on the basis of works but on the basis of grace. This would not be in conflict with the verses in Matt 6 in which we are commanded to lay up treasures in heaven since any good works that we do is produced by the grace at work within us anyway (1 Cor 15:10).
I think it would be good to discuss whether or not there are greater "degrees" of reward that can be stored up in heaven and, if so, whether it is according to good works or grace but, in doing this, let us not neglect also to consider the practical implications of how we lay up treasures in heaven.