As a Christian, how much can we outsource (rely on historical account, science, etc.), and how much scripture needs to be included to refute these heresies?

In our lives, we may outsource our faith. Todays society teaches humanism, creationism, and so many other issues as truth. As a Christian, how much can we outsource (rely on historical account, science, etc.), and how much scripture needs to be included to refute these heresies?Must be 250 words with citation