"Therefore, since we are receiving a kingdom which cannot be shaken, let us have grace, by which we may serve God acceptably with reverence and godly fear." Hebrews 12:28.
"Our responsibility as New Covenant Christians is not to approach Him with a breezy nonchalance. We must serve God acceptably (v. 28) with "reverence and godly fear" (v. 28). The word serve here should be rendered worship. We are to worship God acceptably. This must mean that it is possible to worship Him unacceptably.... And the key note of this acceptable worship is reverence and godly fear. Worship must not be breezy and casual. The Bible says that it ought not to be. And when cultivate breezy and casual worship, we are retarding the growth of the kingdom. One of the fundamental confusions of our era is that which muddles intimacy and informality. The Spirit does cause us to cry out Abba, Father. But the Spirit will never remove godly fear or awe."
- Doug Wilson
And on receiving the Kingdom, also from Hebrews 12:28, same post:
"Jesus taught us to pray, 'Thy kingdom come, Thy will be done on earth as it is in heaven . . .' He did not teach us to pray, "Thy kingdom go, Thy will be done in heaven when we get there after we die . . ."