Today I got this idea:
We should not serve God as slaves, because we are no more slaves, God has delivered as from slavery, as I teach in the book End of Gospel.
But we indeed can serve God for reward. God has promised to reward for righteousness. We can drive nearer to righteousness to receive God’s reward.
If we serve for reward, we are not slaves anymore because slaves serve not for reward.
This does not mean that the reward would be our reason to serve God. We are to serve Him because we love Him. But knowing what God rewards we will know what to do for Him.
This is an incentive to study Bible, to know what God rewards for.
The main idea is that we are not slaves of anybody, even not slaves of God anymore.