Speaking at Chester Cathedral at the start of the Week of Prayer for Christian Unity, Lord Carey gave an impassioned address, sharing with the congregation about the ongoing journey of reconciliation between the Anglican and Catholic Churches.
He spoke of "a new openness in all our denominations towards each other" and "an increasing awareness that our disunity was a disgrace to the good news we all declared we were offering to the world".
He also noted that it is Jesus' mercy that has the power to unite Christians, with God freely pouring his love out to all people.
However, there is still some way to go in reconciling different branches of Christianity, and though believers must "rejoice and celebrate" the progress, Lord Carey noted that it is as yet "not sufficient".
In order to bridge divides and fully unite the Church, the former Archbishop called for an increase in dialogue between Churches and efforts to deepen relationships within individual congregations.
"Where you find true glory you find Jesus: when you find Jesus you find unity and where you find Jesus you find love," he asserted.
Perhaps his strongest statement, however, was his claim that: "There is something far worse than persecution and it is apathy".
"There may be very good will for our churches and our service is deeply appreciated but the message is ignored," he said.
"But this is not the time for self pity or regret. It is a time for us to express our message in terms of love."
He acknowledged that the Church is going through a "difficult time", with many dividing factors such as its position on marriage and sexuality.
"We must not allow ourselves to fracture under the colossal weight of dancing to the world's agenda," he said, suggesting that the Church needs to hold fast in the face of disagreements on more sensitive issues.
His comments follow those he made last year during the Shropshire Light Conference, also in Shrewsbury, when he warned that Christianity is just a "generation away from extinction" in the UK unless churches begin to engage with more young people.
"In many parts of Britain churches are struggling, some priests are diffident and lack confidence, a feeling of defeat is around," he said.
"The burden seems heavy and joy in ministry has been replaced by a feeling of heaviness," he asserted, before labelling public sentiment towards Christianity as dismissive.
"The viewpoint could be expressed in a variety of non-verbal ways: the shrug of indifference, the rolled eyes of embarrassment, the yawn of boredom," he noted.
He concluded his sermon at Chester Cathedral on a more optimistic note, saying: "I have offered you an enormous challenge but we celebrate something far more wonderful – the glory perceived in the Lord who draws us together. And what a destiny is ours and what a hope we offer to the world, for, 'there is nothing in the whole of creation that can separate us from the love of God in Jesus Christ our Lord," he concluded his address.
The Week of Prayer for Christian Unity will run until this Sunday 26 January, during which time Christians are encouraged to prayerfully consider the way in which they can address the "scandal" of disunity between the Anglican and Catholic traditions.