The age of the Earth as calculated by Archbishop James Ussher is a critical component in .

Christianity

Explanation:

Archbishop James Ussher was a renowned professor of Theology and an astronomer. He calculated the age of the earth by studying ancient Hebrew and Egyptian books and he deduced that the world begun on the 23rd of October 4004 BC.

His calculation became a critical component in Christianity because when English Bibles were printed, James Ussher's calculation was what was used in  their chronologies. He became popular and his calculation was as respected as the Bible itself.

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