Westminster Shorter Catechism

Q. 16. Did all mankind fall in Adam’s first transgression?

A. The covenant being made with Adam, not only for himself, but for his posterity; all mankind, descending from him by ordinary generation, sinned in him, and fell with him in his first transgression.

Gen. 2:16-17; Rom. 5:12; 1 Cor. 15:21-22.