The earliest christians were being warned that they were in danger. One of the dangers they faced was described in Hebrews 12:18-24. They were falling into fear; fear of loss, fear of God and fear of failure.
The Hebrew writer reminds them that they do not stand before a God who is defined by a fearful, smoking mountain or a blood soaked temple. He reminds them that they now stand in the presence of holy angels, holy men and a holy God who through Jesus Christ has made it possible for them to inhabit the "heavenly Jerusalem" with joy and gratitude.
The good news for them and for us is that our service to God, our worship, and our service to others is motivated by gratitude rather than fear. Thankful for what we have received we openly confess our allegiance to a Father who has openly confessed His allegiance to us. Who we stand before and why we stand there makes all the difference in how we stand.