I know that Superman is secular, but I have studied alot about Superman and the creators, Joe Shuster and Jerry Siegel. They were of a Jewish heritage and created Superman after Biblical characters like Moses and Yeshua.
Some of the similarities I see between Yeshua and Superman are:

Both Yeshua and Kal-El were sent to earth to be its savior.
Both Yeshua and Kal-El were raised by a humble hard working couple.
Both Yeshua and Kal-El go to their fathers for help.
Both Yeshua and Kal-El picked jobs that were useful in helping them fulfill their destiny. Clark became a reporter at The Daily Planet to keep his finger on the pulse of the world and Yeshua became a carpenter and learned how to be a man of the people.
Both Yeshua and Superman are beaten almost to death, stabbed in their sides, and then killed.
Both Yeshua and Superman rise again.
Both Yeshua and Superman come back again to finish their tasks.
Yeshua is a great friend, as is Clark Kent. Of course, you know there is something different about this friendship. It is not based on selfishness and popularity. It is based on love and sincerity. You know there is something special about this friend.
Just as Clark Kent is Superman, Yeshua is our Savior.

I found many things in the movie, Superman Returns that I feel are like being a Christian.
When SUPERMAN is lifting the Kryptonite infested landmass out of the water, it reminds me of when Yeshua is on the cross and has all of MY sin on his back. It is dangerous to him, it is hurting him, but he keeps taking it. He took it away from me, so I wouldn’t have to be punished by it. Just as Superman took up the Kryptonite mass til it is gone into space, so that it wouldn’t hurt people, Christ took my sin into the grave, so it wouldn’t hurt me.
Then from all the pain he endured from taking that away, he falls to earth. He is pretty much dead. He is in a coma. The doctors can’t do anything to help him. So in saving billions of people, his life is taken. Just like Yeshua who sacrificed his life for me and you. But then like the Triumphant Resurrection of Yeshua, SUPERMAN comes back and is completely healed.
There is a part when he is talking to Lois Lane about her article “Why the World Doesn’t Need SUPERMAN.” He says, “You wrote why the world doesn’t need a savior, but everyday I hear them crying for one.” How moving is that?? Can you hear Yeshua saying that to us?? We, who get so caught up in our own little world and lives, thinking that we have everything we want and how we are just fine with not having anybody tell us what is wrong or sinful in our lives, saying, “Everyday I see that you do need a savior to come in and help you.” It was just profound to me. I can just hear Yeshua saying that to ME!!

Superman has brought many things to light for me as a Christian. There are many things that we can take from him and apply to our lives.
We as Christians are like Kryptonians. Their weakness is Kryptonite, ours is Sin. They have a defense against Kryptonite: Lead, we have one too: the Bible.
The Lead conceals and contains the power of the Kryptonite. The Bible, along with ADONAI, helps us conceal and contain our sin and helps us overpower it. And we come out as healthy as or more so then we went in, but not without scars sometimes. But as with the Kryptonite it cannot be destroyed, just like our sin cannot be destroyed, but you will know how to handle and contain it, and with ADONAI’s help you can overcome it.

We hate and love our sin/flesh nature. Our sin/flesh nature wants to be in control of us and if we let it, it will ruin us. How can we be what ADONAI wants us to be if we are fleshly sinners? We have to condition our flesh to be under submission to the power that ADONAI has given us to help us defeat the sin/flesh nature and Satan.
Our sin “wants to be found”. It will stay hidden for a while, but it “wants to return to his master”, it “hears its masters call”.

We have to throw our sin over board, like in Pirates of the Caribbean when the Black Pearl is chasing them. They have to get rid of everything that is weighing them down to get far away from them. That is how we should be with sin: throwing it overboard. It will only hurt us the longer we hold on to it. We have to let it go and be free. And just like when they turn the ship and surprise the Black Pearl, Satan does not expect us to give up our sin to ADONAI and when we do he will try his hardest to throw another sin at you that you are going to struggle with.
We will always have sin. It is a part of life. Ever since the garden, humans have been struggling with sin. IT WILL NOT GO AWAY. We have the choice to repel that sin or embrace it. Often more times than not we embrace it and the repercussions that we have to deal with are not easy. It is hard and it hurts. We will always have to deal with sin.
Satan knows what your old sins are and he knows your fear that you will not want your children to sin the same way you did, so he will try every which way to make sure that they will commit that same sin or a worse one. He doesn’t forget your sins, he wants them to come back and haunt you forever. He lost you to Christ and he will try his HARDEST to get your children. He doesn’t want them lost to Christ.
Your firstborn will be attacked the worst. ADONAI wants the first of everything, so naturally Satan wants them too. That is why he is Satan in the first place, he wanted to be first in heaven and he wanted to be like ADONAI. So naturally he wants everything that ADONAI has and everything ADONAI wants. Satan has been trying since the beginning of time to make sure he has all the power, but we know that ADONAI has it all. Satan knows deep down that he doesn’t actually have any power and he knows that his power will be taken away from him someday. So he will try to use up as much of it as he can and take as many as he can with him. Are you gonna be one of them?