Native-American poetry

Carlos Montezuma writes almost with rage; his infuriated tone inspires Indian pride and strength.  His parallel structure such as in "Steady, Indians, Steady" is reinforced by the repetition of such phrases as the title.  Like the tone, these elements inspire as well as fortify the Native-Americans and their culture.  Zitkala-Sa's tone is very different; in "The Indian's Awakening", the speaker opens with a somewhat defeatist tone.  However, through the Divine, the speaker is rejuvenated and inspired.  He/she discovers that though in the earthly world, the Indians may be persecuted, in the Spirit-world, their supremacy prevails.  Zitkala-Sa's tone inspires hope and in turn pride and strength.  Though the two poets take different avenues, the end game remains the same.  I was a little confused though in these readings; I was under the impression that the native-american religion focused on spirits of nature rather than really a god.  However, in the poems we read, God is a central element of hope and redemption.  Were the Native-Americans Christianized or did they always believe in God but with spirits in nature as well?