The Old Testament is a collection of religious texts that form part of the Christian Bible. It includes books written by prophets, such as Isaiah and Hosea. Isaiah was a prophet in the 8th century BC who wrote the book of Isaiah, which is one of the major prophetic books of the Old Testament. Hosea was a prophet in the 8th century BC who wrote the book of Hosea, which is also one of the major prophetic books of the Old Testament.