His comments come mid-way through the Lambeth Conference – a gathering of the worldwide bishops of the Anglican Communion which takes place just once every ten years.
The conference has been marred by a large portion of conservative bishops boycotting in protest over the gay clergy issue.
There have already been clear indications of the tensions among delegates, with some bishops expressing their frustration that the conference still has not openly discussed the topic of sexuality within the Church.
In particular, Archbishop Gregory Venables, from South America, told the BBC that there was "frustration" that sexuality had yet to be discussed. The Archbishop, who is the senior Anglican bishop in South America said there was "some suppressed anger" from people wanting to talk about a topic which he described as the "elephant in the living room".
"I think it's because we don't know how to approach it," he said.
Dr Williams' sermon was delivered at St Dunstan's Church in Canterbury, and broadcast on BBC Radio 4's Sunday Worship programme. In it, he told bishops that it was time to "tell each other and the world" about the Church's most important job - to tell people "Christ is here; you're not alone".
He added that the Church "has to look like a solace where people don't seem to be alone or trapped, anxious and fearful, a place where people seem to live in a larger, more joyous and hopeful atmosphere, and where they are treasured and nourished as precious images of God".
"Churches that are divided and fearful and inward-looking don't easily give that message; and our Anglican family badly needs to find some ways of resolving its internal tensions that will set it free to be more confidently what God wants it to be," he said. "Part of our agenda at this conference is to do with this."
About a quarter of the Communion's 880 bishops have boycotted the conference. The current rift stems largely from the consecration of the openly gay bishop of New Hampshire, Gene Robinson.
Bishop Robinson was not invited to the conference, although he has taken part in a number of fringe events
The three-week conference, taking place at the University of Kent, is due to end on 3 August.