Mi hermana está el perro. juega jugando jugar jugaste

Okay so i'm taking an online spanish course (penn foster), and in the study guide, you have to create a bunch of sentences with words you've learned so far. translating, reading, and those kinds of things are fairly easy, but when it comes to making my own sentences, my brain just kinda waltz's away. anyone got any tips?

Son cristianos pero no creen en la autoridad del papa ni en la intercesión de la virgen maría.

De que habla este parrafo? what is this paragraph talking about?