In Your Opinion: Is it Possible for One to be a Christian and a Humanist, or are they Mutually Exclusive?

They are not mutually exclusive, although it would be an unusual form of Christianity. Christianity is typically quite authoritarian (what with the authority of God and all) and humanism rejects dogma, but I think there are some denominations that could possibly qualify (like liberal Quakers). The bulk of Ecclesiastes seems to be written by a theistic humanist (with the last few verses added by some champion of authoritarian orthodoxy), so it's possible.