The whole poem consists of an extended metaphor, which incorporates personification, anthropomorphism, and symbolism. (For more on the first two, see the Personification entry in this section. For more on the last one, see the Symbols section.)
Throughout the poem, the speaker compares the earth to a beautiful woman fending off the aggressive advances of philosophy, science, and religion. Though the genders of these personified "characters" are never stated, they are strongly implied, especially in the passage about "religions" (lines 14-18). These lines seem to accuse religion of assaulting the earth, figuratively speaking, in hopes of impregnating her with "gods." Basically, they accuse religion of trying to subjugate the world.
In general, the poem portrays philosophy, science, and religion as overly aggressive, male-dominated pursuits. They are human disciplines that claim to be learning about nature, but (the poem implies) actually want to control nature. Like lecherous men pestering a woman, they persistently engage with her but don't respect her. As a result, she never truly reveals herself to them.
Meanwhile, earth/nature stays faithful to her preferred "lover," "death," with whom she produces "spring" after the lifeless season of winter. Here, spring seems to represent the kind of beauty and vitality that philosophers, scientists, and theologians can't master (at least according to the poet, who may believe that poets can!). It also reminds these intellectuals that the human intellect can't control life and death. In fact, "earth" and "death" have power over human beings, not the other way around.