What do the speaker's tears represent in the poem, The Altar?

The speaker's tears represent the labor of leading a Christian life as well as the labor of writing poetry. The speakers says that the altar he presents to God is made of his heart and "cemented with tears" (2), suggesting that work and sacrifice is what holds him together. In the same way, the poem itself is also a type of altar for praising God, and the tears represent the labor of the poet to compose the poem.