Pope Benedict XVI has asked the faithful for their help in enabling him to "bring unity to the Church and "faithfully accomplish the task Divine Providence has placed upon me as Successor to the Apostle Peter" after coming under fire over a series of avoidable public relations mishaps and his rehabilitation of ultra-conservatives.

In his Angelus prayers on Sunday, the Feast of the Chair of St Peter, the Pope referred to the episode of the paralytic whom Jesus forgave and healed, which he said "shows that not only did Jesus have the power to heal a sick body, but that he also had the power to forgive sins.”

He added: “Physical healing is a sign of the spiritual healing his forgiveness produces. In effect, sin is a sort of paralysis of the spirit from which only the power of God’s merciful love can free us, allowing us to get up and restart our journey on the path of goodness.”

The Pope's decision to revoke the excommunication of four breakaway bishops from the ultra-conservative Society of St Pius X, including Bishop Richard Williamson, who denies the existence of Nazi gas chambers, continues to rumble on despite the Pope's explicit condemnation of Williamson's views and a promise by the bishop to "review the historical evidence".

There is also unease in the Church over Benedict's naming as Bishop of Linz in Austria Father Gerhard Maria Wagner, who had said that Hurricane Katrina was retribution for the activities of abortionists, prostitutes and homosexuals in New Orleans.

Pope Benedict is criticised by some in the Vatican hierarchy - and outside it - for his "remote" style of governing and his reliance on a handful of close advisers. Last week the Vatican had to backtrack after giving the mistaken impression that the Pope had turned down an invitation from Gordon Brown, the British Prime Minister, to visit the United Kingdom. It at first said no such visit was under consideration, but later said the pontiff would welcome the opportunity to travel to Britain when his calendar allowed.

The Pope said his job as successor to St Peter was to "protect legitimate differences while at the same time assuring that such differences do not hinder unity but rather contribute toward it". He asked the Virgin Mary to "help us to begin Lent, which starts next Wednesday with its suggestive Ash ritual, in the right state of mind".