The 54-year-old Downton Abbey actor travelled through Jerusalem for the American documentary, Jesus: Countdown to Calvary, speaking with academic experts and spiritual leaders to "deconstruct the week leading up to Jesus' death and untangle the complex factors that resulted in his crucifixion".
Speaking in Israel for the trailer of the 60min documentary, he said: "This is a place where history and faith come together.
"Whether you are a person of faith or of none, you cannot escape the fact that the last six days of this man's life, and his death, changed the world.
"I'm not going to chart the religion that grew out of these events. I'm interested in the events themselves: what happened in that final week of Jesus' life, how he died, why he died and who killed him."
The documentary will air in America and Ireland this month, produced for Irish broadcaster RTE with European cultural network ARTE and American Public Television.
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