Original Sin

As Bruce Springsteen once wrote: "They say Eve tempted Adam with an apple
But man I ain't going for that"- Well, neither is Lawrence. OP, who writes, about a wallpaper he created:

"Of course, I need to add as a theological point, that the fruit of the tree of the knowledge of good and evil was not an apple. Rather, there is a pun in Latin: 'mala' is an apple, 'malum' is evil. I think this is how the apple became identified with the eating of this fruit, an act of disobedience to the divine will, through which sin entered the world." An interesting thesis and no doubt a contributing factor, but I think the literal understanding of the forbidden fruit of the tree is more complex.

(Diaconal bow to the Ironic Catholic)

While I am on the issue of sin, there is a post on The Cathedral of the Madeleine RCIA Blog regarding Purgatory, which is an effort to answer some questions regarding this doctrine of the faith.