Why were slavery and the american ideaal of freedom in tension during the writing of the declaratoin of independence?

Slavery and American Ideal of freedom was in tension during the writing of the declaration of Independence for many reasons. For example, America was just becoming it's own country, they were declaring independence from Britain. Now they are on their own and not under Control of Britain, they had to make some decisions on freedom and slavery. They believed that all men should be free ... but at the same time believed in Slavery. That is why there was tension. They were becoming a new country and people have different opinions and view on slavery and freedom.