You can't understand about 300 years of European history, or Shakespeare, or the Enlightenment philosphers who laid the groundwork for modern democracy; without a basic understand of the religious arguments.
By that reasoning, and considering the religious wars being fought around the world today, we should also teach other holy books - the writings of Confucius, Bhagavad Gita, I Ching, the Koran, the Talmud, Tao-te-ching (Taoism), Veda (Hinduism).
The Bhagavad Gita, the I Ching, etc. have not profoundly influenced the English language or English literature. The Bible has.
Just because a piece of literature bears religious significance for a group of people does not mean that it should be completely banned from the public school curriculum. Greco-Roman mythology including the Illiad and the Odyssey are often taught in public schools.
Religious instruction and evangelism, however should not be part of the curriculum. Unfortunately, that is sometimes the intent of those advocating for Bible classes in public schools.