What is the main theme of the poem E. E. Cummings?

E. E. Cummings is a poet, not a poem, and he wrote a lot of poetry, so there is no way to know which theme you mean... many of them were love, or sex, or hope... but no way to know for sure without knowing which poem you mean.

You might try finding the title (usually the first line of the poem, since Cummings often didn't title his poetry) and asking again with the title included.