I’m a couple of days late with this, but here is the Collect for the Second Sunday after Christmas from the Order of Worship for the Reformed Church in the United States.
It turns on the same general theme as the Collect for this Sunday in The Book of Common Prayer, but is slightly longer and draws out more clearly the implications of living union with Jesus Christ and the conformity to him that is the consequence of that union.
The Collect
ALMIGHTY and everlasting God, who by thine only begotten Son hast made us to be a new creation for thyself, and hast bathed us in the new light of thine Incarnate Word; preserve in us, we beseech Thee, the works of thy mercy, and cleanse us from all our ancient stains; that by the assistance of thy grace we may be found in his form, in whom our substance dwells with Thee; through Jesus Christ, our Lord. Amen.