You Shall Know the Truth, or A Catholic Catechism, was a series of 50 radio programmes recorded by Archbishop Fulton J. Sheen in the 1950s. Covering the whole sweep of the Catholic Faith, this catechism is ideal for adults wishing to brush up on their faith. The link below is for the episode on Original Sin. Others can be found on the Pro Ecclesia et Pontifice website. They are all well worth listening to.