Dear sir - you have been appointed an agent of the american anti-slavery society…

object is, the overthrow of american slavery, the most atrocious and oppressive system of bondage that has ever existed in any country. we expect to accomplish this, mainly by showing to the public slavery’s true character and legitimate fruits [real effects] contrariety [opposition] to the first american principles of religion, morals, and humanity, and its special inconsistency with our american democratic aims, as a free, humane, and enlightened people. in this way, by the force of truth, we expect to correct the common errors that prevail respecting slavery, and to produce a just public sentiment, which shall appeal both to the conscience and love of character, of our slave-holding fellow-citizens, and convince them that both their duty and their welfare require the immediate abolition of slavery… slavery is un-american.

based on this document, what was one argument the american anti-slavery society planned to use to promote abolition?