Gran Torino is a move about Walt Kowalski, as played by Clint Eastwood, is a Christian movie. Now that doesn't mean that it has anything to do with God, or even Christ. I define a Christian movie as being a movie based on a Christian worldview. For more details about what I consider a Christian Movie, please consult Blood of Prokopius [http://bloodofprokopius.blogspot.com/2017/01/why-i-dont-like-most-modern-sci.html], as he's the one who created the definition. For another example of a Christian movie, look his example, Kung Fu Panda. And yes, it's serious.
First, we have a Po. Po is a clumsy, nerdy, and chubby young man who has no idea what he wants to do with his life. But throughout the three movies we see him overcome his flaws, his preconceptions, and his circumstances to become the Dragon Warrior. And Po does not do this through his own ability, but by tapping into something greater than himself, and thus being transformed by it. This is the Divine, and it allows Po to become more than who he who. In a world without the Divine, Po is trapped by who and what he is, and nothing can overcome that. But instead, Po can become someone else by realizing that even he has a role to play, and a purpose greater than himself to serve.
So a Christian movie is a movie where the Divine exists, and where the characters need it to overcome themselves and the world. And so Gran Torino is a Christian movie.
Walt Kolwalski begins the movie as a bitter old man attending his wife's funeral. His own family do not seem to respect the occasion or him, and he's alone. But circumstances conspire to place him in the company of his next door neighbors, a group of Hmong immigrants from Vietnam. When the neighbor's eldest son is pressured to join a gang, he is asked to steal Walt's 1969 Gran Torino. But in the attempted robbery, he mucks it up, and Walt is waiting for him in the garage with a gun. The boy, who is named Thao, predictably flees, managing to escape in the process. Later the gang returns to educate Thao on why failure is not tolerated in their organization, only for Walt to show up again and run them off.
This causes the neighbors to shower Walt with kindness, as well as a request. They ask him to take care of Thao, to mentor the boy and help him become a man, as he has no father. Walt agrees, as he is sympathetic of Thao's plight. And through his relationship with Thao and the neighbors, Walt comes to love them dearly. Thus, when Thao's sister is attacked, Walt locks him in the basement and goes to get revenge, supposedly. And when he arrives at the gang's headquarters, he dares them to attack him. And when he reaches for his gun, they open fire on him and kill him.
But Walt had no gun, he was only reaching for his lighter. Walt willingly embraces his own death, and sacrifices himself for his friends and neighbors. In doing so, he transcends his own selfishness and bitterness, and unites with the divine. Walt is transformed through the power of the divine, and thus overcomes his flaws to be transformed into something beyond his expectations or hopes.