This study aims to explore the origin of American racism and the construction of multiracial subjects in Toni Morrison`s A Mercy. Going back to the 17th century American colonial times when everything was fluid and any poor person could be a slave regardless of race, Morrison explores the historical fact that racism was not an inherent ideology in America but the product of politics of the colonial white power who feared the alliance of poor whites and black slaves, especially after Bacon`s Rebellion. Along with the politics, the 17th century Christian discourse based on the exceptionalist myth that they were “chosen people” contributed to producing racism by differentiating themselves from native and black people. In this historical frame, Morrison explores the way major characters in A Mercy are constructed as a colonizing or colonized subject according to the different position offered by the dominant discourse based on race, gender, and class. In the text, they show an identity `in process,` constructed on the boundary between the social and the unconscious. However, in representing the colonized subjects, Morrison assumes the construction of an identity which serves the subject`s interests, a politically strategic identity. In other words, in the crisis of loss of self caused by racism and slavery as shown in the cases of Florens, Lina, and Sorrow, the colonized subjects need to reconstruct themselves and establish a definable, `irresistible` identity in order to resist racism and sexism and create a positive image about themselves.