I don't think we particularly disagree, but I see no reason personally to enshrine the philosophy of people who are against God. Let the disciples of the atheists do what they will, but always rebuke them in the open squares with reason, lest the common people be swayed by falsehoods. To that end, we should be well-informed of historical and modern heresies, such that we are amply prepared when we are called upon to defend the faith.

I am not so sure that the reason you cited was the fundamental reason that the right 'lost' the culture war in the 60s. Communist infiltration of western institutions was already ongoing by then.

TLDR: I don't think people like Sagan should be censored - far from it, but I don't think it's the place of the church to teach about secular anti-church ideas or keep a record of them except as a topic for apologia and a warning to future generations. If Sagan did any valuable scientific work, let the scientists revere him as they wish.