What is the function of this sentence?

Because of the jealousy of Persian officials, Daniel was cast into a den of lions. He was delivered unharmed because of his trust in God.

to state theme

to describe plot

The function of the given sentence above is to describe the plot. A plot in literature is used to describe the series of events that make up the story. In the sentence above, it just merely describes the situation of Daniel and what happened to him due to the jealousy of Persian officials.