Admitting a mistake need Courage. How do you view on this news, 400 yrs late: Vatican honours Galileo?

That it took 400 years to admit a mistake is nothing to be proud of. Did the followers of this religion believe the erroneous conclusions of the Vatican for the last 400 years, and only now accept the truth? Is truth justified on itself or what the Vatican says? What other admissions of "mistakes" need to be made, and how many hundreds of years will they take?