seated at the right hand of the Father

...When He had made purification of sins, He sat down at the right hand of the majesty on high...(Hebrews 1:3)

Jesus, after dying on the cross for the sins of all humanity and making purification for ours sins, trampled down death by death and rose from the grave so that, ascending into heaven He might be seated at the right hand of the Father. Again turning to the Nicene Creed, we find this confession:

On the third day He rose again
in fulfillment of the Scriptures;
He ascended into heaven
and is seated at the right hand of the Father.

But, we might ask, why (if at all) does it matter that Jesus is "seated," and why (if at all) does it matter that Jesus is "at the right hand of the Majesty on high" (Hebrews 1:3)? By turning our attention to these facets of Christ's role in redemption, the author of Hebrews introduces us to the significance of both Jesus' heavenly posture and position. To better understand the importance of each of these aspects, we will consider an analogy from God's creation of the universe (and all that is) as well as draw from a portion of the doctrine of the Incarnation that Paul details in his letter to the Philippians.
Recall that when God created "the heaven and the earth and the sea and all that is in them," He rested from His work on the seventh day because it was completed (Genesis 1; Psalm 146:6; Nehemiah 9:6; Acts 4:24; 14:15; Genesis 2:2-3). Similarly, by being "seated" at the right hand of the Father, Christ has entered into a posture of rest because His sacrificial work is complete, having been offered "once for all" (Hebrews 7:27; 9:12; 10:10; 1 Peter 3:8). This posture is significant because it reveals his superiority over the former Levitical priesthood (see, for example, Hebrews 7:23-28). The priests of old were "weak" as a result of their mortality in addition to their own sinfulness. Moreover, the sacrifices offered at their hands only provided a covering, and could not offer absolute purification as does Jesus, since in the ancient sacrifices "there is a reminder of sins year by year" (10:3-4, 11). As a result, the Levitical priests by necessity would first offer sacrifice for their own sins before the sins of the people and, additionally, they offered sacrifices year by year until their own death prevented their work. Furthermore, since their work was never finished, they could never rest from it, but repeatedly offered sacrifices while on the earth.
The writer of Hebrews crucially notes that "Jesus, on the other hand, because He continues forever, holds His priesthood permanently" (7:24). Yet, though Jesus is the eternal High Priest, this does not mean that he repeatedly makes offerings for sin throughout eternity. Rather, Jesus offered Himself once for all time and has rested from His work in that His offering is perfect and complete. So, Jesus has entered into a posture of rest, and is "seated."
Turning to the second aspect, that of position, we read that Jesus is "seated at the right hand of the Majesty on high" (1:3, emphasis added). A typical concern that arises in reaction to this proposition is whether or not it implies Christ's subordination to the Father, the Majesty on High. Yet we must remember to retain the full context of this statement, both in the book of Hebrews as well as in the whole of Scripture. We have already seen that in the first verses of Hebrews the writer directly implies Jesus' deity by delineating His role as Creator, Sustainer, and Savior, and by uniting Christ's nature with the Person of God. Conjoining this with the doctrine of the Incarnation, we know that the Eternal Word who "was with God and was God" became flesh and "emptied Himself, taking the form of a bondservant, being made in the likeness of men" (John 1:1; Philippians 2:7). Paul also testifies that Jesus "humbled Himself by becoming obedient to the point of death" and that "[f]or this reason also, God highly exalted Him" (2:8-9). When we consider these aspects in light of Christ's divinity revealed in Hebrews and elsewhere, we conclude that Jesus has reentered into a position of exaltation that He, by His own nature, possessed eternally, though He chose to take on human flesh both "for our sake and for our salvation" and for the glory of God.
What this suggests for us, who frequently strive in our own strength to merit salvation, is that we can find rest in the One Who has ceased from His work and by His own merit obtained for us "so great a salvation" (Hebrews 2:3). Though we should "[never] grow weary of doing good" and should always be encouraged to work out our own salvation with fear and trembling, we must remember that it is God who works in us to will and to work for His good pleasure (Galatians 6:9; 2 Thessalonians 3:13; Philippians 2:12-13). We have no need for fruitless efforts of sacrificing again and again to be cleansed from sin because we can be sure that Jesus, "having offered one sacrifice for sins for all time, sat down at the right hand of God" (10:12). For us, He is and always will be enough.