This opening salvo immediately puts the focus on the Son of God as the Messenger, the Heir of all things, the Creator and the Sustainer. This was to remind the audience of what and whom they had been neglecting through focusing on lesser things.
Verse 3 contains two distinct actions: Jesus purged our sins and He sat down at the right hand of the Most High. Notice that even though these two actions are mentioned one after the other, there was a space of time between them. His sitting down—His enthronement— did not happen immediately after He purged our sins.
