If this is the theme of worship in heaven, should it not also be on earth? Will eternity exhaust the themes of worship? Will we fail to find new wonders after a time. This doubt only shows the poverty of our thinking. We should have no fear that we will ever grow tired of the glories of redemption. It is the work of the Spirit of God to refresh our minds with the wonder of what Christ has done. If we try to worship God without the Sprit then indeed our own feeble thoughts soon reach their limit. But those who are taught by God are shown the wonders of his grace which satisfy the soul and at the same time hold promise of an inexhaustible supply of glories to come. God is great enough to satisfy our souls forever.
Not all the worship of his people together can add any glory to God. The Lord is not dependant on us for anything. He is perfect and cannot increase in any way. While the unbelieving world begrudges God its praise, his saints see worship as their greatest privilege and his unspeakable gift to his creatures.