The first is on worship. Worship is different now because of the person and work of Christ and the Church's union with him. Hebrews 12.18-29 provides a comparison and contrast of two corporate worship assemblies to illustrate the difference that results in worship because of Christ. Here is a preview:
Through the perfect mediatorial work of Christ and your union with him--your corporate worship becomes subsumed in that great worship service that is taking place in heaven. You don't wait for the heavenly presence of God to come down--you are brought up to that heavenly presence to join in the festal gathering of innumberable angels, to the assembly of Christ and those who are resurrected in him in heaven to serve and worship the triune God through the mediation of Christ. And all of this is now! This is not only future, for notice verse 22, "but you have come." Because of your union with Christ, your earthly worship, Trinity OPC's weekly Sabbath worship, takes place in heaven, because it is into heaven that you have come. Not physically, but spiritually, mystically and truly. . . .You can read all of "Union with Christ and Heavenly Worship on Earth" here.
. . . Worship is to be biblical, spiritual, joyful, grateful, redemption-effected, reverent, awe-inspiring, heavenly fragranced God-centered devotion that manifests who he is and who we now are in Christ.
The second is on the communion of the saints. By nature of union with Christ, the Church comes to share in the fellowship enjoyed among the three persons of the Trinity, and does so, because of Christ's self-sacrificial love, which results in the Church now being built into the new temple of God where love dwells. The sacrificial love of Christ and the Church's new identity in Christ as the new temple are to shape how the saints love one another. Here is a preview:
Through his shed blood, Christ has reconciled us to God and to one another. It is, therefore, inappropriate not to love one another. It is inappropriate to require more of one another than God requires of us. It is inappropriate to view one another differently than God views us. God sees us as righteous in Christ, in whom there is no offense, but only righteousness and love. As Charles Spurgeon once said, "How dare I keep someone off my prayer list that is on Christ's." We all equally together stand before God in Christ. We will all equally dwell together with God in heaven. This, Trinity OPC, should shape your love towards one another: not love that is based on how others treat you, but love that flows from how God treats you in Christ. . . .In Christ we are to love as we have been loved in Christ, as we are loved in Christ, and as we will love in heaven in Christ.
And this heavenly temple is what you are being built into by Christ Jesus. . . . And it is his infinite love that fills heaven and his heavenly temple. . . . The sun never sets there in heaven, for God Himself is the everlasting Sun, whose beams of love gently descnd upon all of His beloved people and shapes the very essence of heaven everlasting moment by everlasting moment. In heaven, all is love. . . .
God is perfecting us, not merely as individuals but as individual parts of the heavenly temple. That is the ultimate end of our salvation. That is why our text tells us that our love for one another is a demonstration of our being God's abiding place, God's temple community. . . . Let us believe that we are the dwelling place of the eternal God; and let us live, then, as His heavenly temple. Let us love one another in anticipation and reflection of that love of the eternal heavenly temple. . . .
You can read all of "Union with Christ and the Communion of the Saints" here.