Please read Fr. J’s excellent Octave of Christian Unity post below. I don’t want to detract from his post, except to say that a few years ago Jonathan and I put together some prayers and readings for the Octave of Christian Unity, with a special focus on East-West unity. Please check out the resources for day one, including this prayer:
Your blessed Son asked that His Church be one
as You and He are one,
but Christians have not been united as He prayed.
We have isolated ourselves from each other
and have failed to listen to each other.
We have misunderstood and ridiculed
and even gone so far as to attack each other.
In doing so we have offended against You,
against all our brothers and sisters in the Church
and against all who have not believed in You
because of our scandalous disunity.
Forgive us Father,
and make us fully one.
Blot out our sins,
renew our minds,
rekindle our hearts,
and guide us by Your Holy Spirit
into the oneness that is Your Will.
Prayer for the Unity of the Church from
the New St. Joseph People’s Prayer Book