Wrong. Humanism was an aspect of Greek and Roman philosophy long before Christianity came about. Christianity adopted many of the values seen in stoicism and neo-platonism, for example, which made it more 'moral'. Humanism is not derived from Christianity, but an addition to it adopted from more ancient viewpoints.
Humanism of today is a direct descendant of Christian teachings.
Greek and Roman philosophy is not what is taught in today's world except in school classes. The present day evolved Christian ethos is the de facto basis of our social mores and even political thought.
That is just the way it is. Deal with it.