I just want to point out, that congratulations sounds wrong. It's just weird to congratulate him for doing something for us. Don't get me wrong, I'm a Christian, but I just don't agree with this meme. Saying thank you sounds a lot better than congratulating him for his death.
It's like congratulating your father for giving you something.
I know you made this meme with your heart, and it's somewhat of a thank you to Jesus, but it just seems wrong.