Is the raising and seating of Christ the work of the triune God?
Yes. The power that raised Christ from the dead and seated Him at God's right hand in the heavenlies was wrought by God the Father and God the Spirit—the triune God. Christ did not seat Himself; an outside personage set Him there.
Les explains that the pronoun usage in Ephesians 1:20 identifies God the Father (mentioned in verse 17) and God the Spirit, again the triune God, as the one who raised Christ from the dead and set Him at His own right hand in the heavenlies. He emphasizes that this was done by an outside personage—Jesus did not set Himself down. Les also points out that resurrection is the epitome and high point of everything God has accomplished; if there is no resurrection, everything else falls apart. The context also notes that this seating was previously seen in Hebrews chapter 1.
Which he wrought in Christ, when he raised him from the dead, and set him at his own right hand in the heavenly places,
More Questions
Did Jesus set Himself at God's right hand?
The setting of Christ at God's right hand was done by an outside personage; Jesus did not set Himself down, but God set Him there.