This could also be seen as having duel meaning by emphasizing what the next line has to say because she really wanted to express how grateful she was for being given the opportunity to get an education. Wheatley made a blatant reach at pathos when referring to Africa as her "pagan land". She is asking for the sympathy of the reader by insinuating that she could not have known and better. If you as a reader are ever confused about the meaning of a word you come across when reading it is best to consult the Oxford English Dictionary.
By saying that she was ignorant of a Savior until she was allowed the chance to read implies that the case would be the same for the majority of other slaves if given the chance. She called her soul "benighted". The definition of benighted according to the Oxford English Dictionary is "overtaken by the darkness of night". This is admitting the ignorance she had on such topics in the past. The second line is the end of the introductory couplet and in just two lines she provides brilliant insight to the context of the poem. She finishes the couplet by giving herself credibility for the rest of the poem by claiming that she understands about Christianity now.
The second couplet serves to introduce God as the central focus of the poem while at the same time hinting at the argument that slavery and Christianity cannot coexist. Wheatley begins the second couplet by claiming "there's a God". This is giving her further credibility with her audience as she is making a statement that they all strongly agree with. This serves as evidence building to put herself on the same intellectual level as her readers as she is probing that she is enlightened and truly understands. This sort of proclamation is just the kind of language that will take deep hold with her Puritan reader base. The second claim in the third line that "there's a Savior too" even further points her argument in the direction she is getting towards.
