This is in no way, shape or form an article based on preaching the word of religion or claiming that I know any actual inspiration behind the story. This is written by someone who has recently watched the movie and noticed a recurring message.
1. Deon is portrayed as God
Deon asks Chappie to respect him, as Deon designed him and made him. This draws obvious parallels with God, who commands respect from humans, claiming that they should worship and respect him as their superior.
2. Chappie is Adam
Chappie is instructed not to do the heist by Deon, and since he is his creator, he should follow Deon's instructions. Chappie obeys, just as Adam did when God instructed him not to eat from the Tree of Knowledge.
3. Ninja is 'the serpent'
Ninja encourages Chappie to go against Deon's instructions, coaxing him to do the heist with the gang. This is similar to the serpent encouraging Adam and Eve to eat the forbidden fruit, after God instructed them not to eat the fruit.
4. Chappie eventually represents a non-believer
Chappie eventually falls out with Deon when he realises that there is no way to save his body. Simplified, Chappie was born to die, similarly to humans. In reaction to this, Chappie commits crimes (sins), due to his faith being lost.
5. Deon shows God is forgiving
Even after Chappie went against Deon's instructions, Deon still forgives him, making it clear that he still loves Chappie. This is representative of God's forgiving nature, as he forgives those who have sinned.
Thanks for reading!
Please don't think I'm preaching, I just thought it was a cool theory.