Dr. Paul Sawyer of Cornell University says that the "the primal sin of Renaissance (was) self-division." He means that the heart and the head had to be united in order for a man to fully serve God.
We see evidence of this argument in Canto XI. Virgil shows Dante those souls tormented because they have relied solely on their intellect:
"From divine intellect and divine art.
And if you pore over your Physics closely,
You’ll find, not many pages from the start,
"That, when possible, your art follows nature
As a pupil does his master; in effect,
105 Your art is like the grandchild of our God.
"From art and nature, if you will recall
The opening of Genesis, man is meant
To earn his way and further humankind.
"But still the usurer takes another way:
110 He scorns nature and her follower, art,
Because he puts his hope in something else.
In modern thinking, this sin may still resonate, but most Christian doctrine relies on the requirement to accept Christ as savior. Not to do so is the greatest sin. The "primal sin" is not self division.