I grafted you into the tree of my chosen Israel,
and you turned on them with persecution and mass murder.
I made you joint heirs with them of my covenants,
but you made them scapegoats for your own guilt.
Holy God, holy and mighty,
Holy immortal One, have mercy upon us.
Section on Worship, Board of Discipleship, United Methodist Church, From ashes to fire: services of worship for the seasons of Lent and Easter with introduction and commentary, Supplemental worship resources 8 (Nashville, TN: Abingdon Press, 1979), 158 (where it is reproach/improperium no. 9 under the section labelled "SILENT MEDITATION or DEVOTIONS AT THE CROSS"). "Don E. Saliers of Emory University was the writer of the [entire] manuscript", composed in sporadic consultation with James F. White and Hoyt L. Hickman (8-9). The only even remotely potential antecedent could, I suppose, be "the excellent work done by the Inter-Lutheran Commission on Worship" (161), but I think that likely to have involved work on the traditional Reproaches in general rather than the composition of this one stanza in particular de novo.
Cf. p. 56 here, though, significantly (?), not pp. 310 ff. of the Church of England's Common worship: Times and seasons. Cf. p. 647 of the Acknowledgements to the latter. It appears also on p. 189 of Hickman, Saliers, Stookey, & White, The new handbook of the Christian year based on the Revised Common Lectionary (Nashville, TN: Abingdon Press, 1992). It does not appear in the 1992 United Methodist book of worship.
I wonder if there aren't some objections additional to those made by N. T. Wright.