Today he is challenging his parishes to open their doors and to welcome people in.
In a video message for the New Year, posted today on the diocesan website www.chichester.anglican.org Dr Warner backs the worldwide Year of Mercy initiative of Pope Francis as a way towards better realising "our vitality and confidence".
"We opened a special door in Chichester Cathedral early this month which is called the door of mercy.We want people to feel that they are welcome [in our churches] as we recover our vitality and confidence as Christians," says Dr Warner in the film.
Pope Francis, who opened a holy door at the Basilica of St Peter in Rome on Dec 8 said: "the time has come for the church to take up the joyful call to mercy once more. It is time to return to the basics and to bear the weaknesses and struggles of our brothers and sisters". Millions of pilgrims will pass through the holy door including Dr Warner and a party from Sussex when they visit Rome in the Spring.
Dr Warner, who invited Bishop Richard Moth, Catholic Bishop of Arundel and Brighton to the Chichester Cathedral door of mercy opening, believes the Pope's challenge applies to every Christian of every denomination.
"In a society and culture where people often feel alone, bereft, anxious and confused - the sense of a merciful God who knows you and loves you is a powerful statement for all our parishes across Sussex," Dr Warner explains.
The Bishop has launched a five year strategy encouraging growth and vitality in churches right across Sussex. Each of the five years will have a themed approach encouraging revitalisation and renewal.
2016 as the Year of Mercy will be followed next year by the Year of Scripture.