Some GLOs are Christian based or have many references to God. For example, my Fraternity, Kappa Sigma, while historically based in Christianity, is open to people of faith. If you take our public creed, we have references to God and faith.
"The Star and Crescent shall not be worn by every man, but only by him who is worthy to wear it. He must be a gentleman... a man of honor and courage... a man of zeal, yet humble... an intelligent man... a man of truth... one who tempers action with wisdom and, above all else, one who walks in the light of God."
I am a spiritual person and have never felt, in my Fraternity, that my spirituality was being turned to a wrong or negative direction. So my advice is follow your intuition and heart. Find a Fraternity that fits your morales and beliefs and you'll be fine