Then why does the RCC teach evolution if the Bible is true?
Why didn't the Pope correct the Bishops who say the Bible is not true?
Is our salvation dependent on a literal understanding of Genesis? No, of course not, but it is important to understand that God is the cause of all, and that is the bottom line of the creation story.
Why didn't the Pope correct the Bishops who say the Bible is not true?
They didn't say it wasn't true, they said that hyper literalism is potentially dangerous and can causes people to lose focus on the real purpose of Scripture.
People tend to forget that God isn't bound to the limits of either our ability to understand or our ability to communicate via the written word. If I tell my child that the sun rises in the east and sets in the west, I'm not accurately describing the mechanics of the interplay of the earth's rotation around it's axis and it's rotation around the sun in the sunrise/sunset scenario, but the child understands that the sun rises and sets, giving us day and night.