He re-affirmed the Christian commitment to social justice and caring for the most vulnerable rooted in the command of Jesus to love God and neighbour.
"To live out [our] faith includes to take responsibility for the living together in society," he said. "Trusting in God and loving your neighbour are two sides of the same coin.
"Therefore we see it as our task to stand up for justice, to combat discrimination and marginalisation, to promote peace and sustainable development.
"All these are shared principles of Christian churches around the world."
G8 leaders are due to discuss a number of problems, including global warming and soaring fuel and food prices.
Bishop Huber said that the climate crisis revealed the extent to which humans were behind much of the "destruction of natural conditions for life".
"Undoubtedly the rich and industrialised countries have contributed and continue to contribute in an irresponsible way to the climate change with its enormous destructive impact on all people, in particular on the poor," he said.
Bishop Huber said that highly industrialised nations were "obliged" to adopt methods of sustainable energy production and consumption and move beyond simple adaptation to global warming, to limiting the process.
Other plenary sessions over the course of the two-day summit include "Advancing Shared Security: The Commitments of the World's Religions", and "The Way Forward: Mobilising the World's Religious Communities in Common Action for Peace".
Summit delegates will later present their proposals to Japanese Prime Minister Yasuo Fukuda, the chair of the G8 Summit.
The Group of Eight is composed of the world's most powerful countries whose government leadership meet annually to discuss global issues. The G-8 is composed of Canada, France, Germany, Italy, Japan, Russia, the United Kingdom and the United States.
