Throughout the series there are many musical performances that have religious themes. Specifically “Grilled Cheesus” because the episode is based on religion. They take songs that would be normally mainstream and make them somewhat spiritual. Mercedes sings “I Look to You” by Whitney Houston when she finds out that Kurt’s father Burt has had a heart attack. The chorus says:
I look to you
I look to you
After all my strength is gone
In you I can be strong
“You” in this context is obviously referring to God. She is encouraging Kurt that he can turn to God when he’s troubled and his strength is gone. She is also saying that God can provide him with strength, which is a difficult thing for a atheist to hear. Mercedes also sings “Bridge Over Troubled Water” with her church choir. Again, proving that she is steadfast in her faith and showing Kurt that he can lean on God when he goes through hard times.
In the same episode Finn sings “Losing My Religion” at the end. Which is sort of a joke considering he jumped on board with religion so quickly because he saw the face of Jesus in his sandwich. The interesting thing about this is that some religious people would indeed take this as a sign and Finn does too… for a short period of time. Once things no longer go his way, he “loses his religion”. Many people also look at religion in this way. People tend to lose faith in God and his existence because of the hurt in the world or the loss of a loved one.
Also, the Glee Christmas albums all feature different Christmas carols that are religious based. Such as Angels We Have Heard on High, Silent Night and Hanukkah, Oh Hanukkah. These songs are essentially about the birth of Jesus Christ or the celebration of Hanukkah.
There are also many other examples of performances that are considered “spiritual”, although not necessarily directly religious.
Religion in Glee 