Why was abolitionism or opposition to slavery a major issue in the US?

Abolitionism was a major issue in the US due to the moral, ethical, and humanitarian concerns surrounding the institution of slavery, which was seen as a violation of fundamental human rights. The movement gained momentum in the early 19th century, fueled by religious fervor, social reform, and the increasing visibility of the brutal realities of slave life. Additionally, the economic and political tensions between the North and South intensified the debate, ultimately contributing to the outbreak of the Civil War. The struggle for abolition not only aimed to end slavery but also to redefine American values and principles regarding freedom and equality.