The Archbishop of Canterbury has warned in his Easter sermon against nations' greed for oil, power and territory.
Dr Rowan Williams said the "comforts and luxuries" we take for granted could not be sustained forever.
He told worshippers: "We face a culture in which thoughts of death are too painful to manage."
Two men were arrested at the start of the sermon, after protesting over comments made by Dr Williams on the adoption of Islamic Sharia law.
Dr Williams reminded the congregation of Christianity's Easter message that death would be overcome.
But he said death was the end "in an important sense", and urged Christians to prepare for it by constantly striving to let go of "selfish, controlling, greedy habits".
The archbishop said: "Individuals live in anxious and acquisitive ways, seizing what they can to provide a security that is bound to dissolve, because they are going to die.
The protestors were quickly arrested
"Societies or nations do the same. Whether it is the individual grabbing the things of this world in just the repetitive, frustrating sameness that we have seen to be already in fact the mark of an inner deadness...
"Or the greed of societies that assume there will always be enough to meet their desires - enough oil, enough power, enough territory - the same fantasy is at work.
"We shan't really die. We as individuals can't contemplate an end to our acquiring, and we as a culture can't imagine that this civilisation, like all others, will collapse and that what we take for granted about our comforts and luxuries simply can't be sustained indefinitely.
"To all this, the church says, sombrely, don't be deceived: night must fall."
Two men with placards which read "Support the persecuted church" and "No to Sharia law" stood in front of the pulpit as Dr Williams began his sermon.
The men were arrested and have been charged with causing a disturbance in a church.
Kyle Spotswood, 26, and Sidney Cordle, 52, from Sheffield, have been charged under Section two of the 1860 Ecclesiastical Courts Jurisdiction Act.
The charge carries a maximum penalty of two months in prison if found guilty.
Security had been stepped up at the cathedral, following the controversy surrounding Dr Williams' comments last month.
Canterbury Cathedral spokesman, Christopher Robinson described the incident as a "minor disturbance."
Mr Robinson said: "The Archbishop altered the start of his sermon slightly to rebut their claims.
"He then asked everybody to pray for them, and for all Christians persecuted for their beliefs."