The patriarch of Constantinople made this affirmation when he welcomed a delegation from the Holy See for Monday's feast of St. Andrew, patron of the Orthodox Church.
The Vatican delegation was headed by Cardinal Walter Kasper and Bishop Brian Farrell, president and secretary of the Pontifical Council for Promoting Christian Unity.
Bartholomew said the presence of the delegation in Istanbul "confirms the desire to eliminate the impediments accumulated in the course of a millennium to attain the fullness of communion."
An Orthodox delegation makes a similar visit to the Vatican for the June 29 feast of Sts. Peter and Paul.
"We attribute great symbolic meaning to your presence here, as it also reveals the desire of the Most Holy Church of Rome to do everything possible to regain our unity in the same faith and in sacramental communion, according to the will of the One who has called us to unity so that the world will believe," Bartholomew I said in his message.
He said the path to communion, as lived by the two Churches for the first Christian millennium, "has been undertaken with the dialogue of love and truth."
And, the patriarch affirmed, this dialogue "progresses, by the grace of God, despite the occasional difficulties."
The current theme being tackled by the joint Orthodox-Catholic commission is the question of papal primacy in the first millennium, before the split between the two Churches.
The commission met in Cyprus in October.
"Everyone is aware that this thorny question has caused great contention in the relationship between our two Churches," Bartholomew I observed. "For this reason, to uproot this impediment between us would surely foster our path to unity."
The study of the history of the Church in the first millennium "will also be the cornerstone for the evaluation of other subsequent developments in the course of the second millennium," he affirmed, invoking the gifts of humility and dialogue to accept the truth.