In tomorrow's reading from the Gospel of Matthew, Jesus clearly says that not everyone who thinks they are following him really is--something anyone who calls themself a Christian would do well to remember.
Anyhow, with that in mind this prayer seems particularly appropriate.
Gracious Father, we pray for they holy Catholic Church. Fill it
with all truth, in all truth with all peace. Where it is corrupt,
purify it; where it is in error, direct it; where in any thing it is
amiss, reform it. Where it is right, strengthen it; where it is in
want, provide for it; where it is divided, reunite it; for the sake
of Jesus Christ thy Son our Savior. Amen.