What little is written about John M. Stahl mostly is about Leave Her to Heaven or his other so-called "women's pictures". Stahl's reputation also rests on the fact that two of his films Imitation of Life and Magnificent Obsession were remade by Douglas Sirk. Very few of Stahl's films are available on tape or disc. One key early sound film that would be most welcomed, if still preserved, would be Strictly Dishonorable, Stahl's 1931 film from Preston Sturges' hit Broadway play. What The Immortal Sergeant and The Keys of the Kingdom accomplish at the very least is that they are reminders that Stahl also made at least two worthy films about men.

Although both films were essentially works for hire, they share some key elements. Both films are about men who discover their strengths after being sent to remote parts of the world. Both Fonda and Gregory Peck are encouraged by mentors who die in the course of the film. One could also say that both films are about protagonists who seek balance between following orders and their own inner direction, and between personal beliefs and and a more expedient greater good. Also shared is a core belief of the two main characters in the inherent dignity of others, a respect given to all. Whether as soldier or priest, that respect is accorded everyone regardless of who they are, unless that person demonstrates that the respect is not mutual. Both Fonda and Peck are self-effacing, and view whatever they have accomplished as no more than the job that they were assigned.

The Immortal Sergeant is an unusual war film, especially for its time. Henry Fonda is motivated to enlist not because of patriotic ideals, but because he has seen newsreel footage of how the Nazis have imprisoned his favorite French waiter. Fonda also chooses to enter the war as a Private, playing on the notion that as a civilian his character is a very private person. Even though the Italian and German soldiers are virtually unseen, war is presented as a waste of human life. There are really no winners or losers, just the survivors and the dead. Fonda calls himself a tinpot hero. Military victory is less meaningful than developing a backbone, and considering oneself worthy to propose marriage to Maureen O'Hara.

The Keys of the Kingdom may strike some as being shockingly liberal when viewed at a time when concepts as Christianity and faith seem so narrowly defined. Gregory Peck's Father Francis chooses to have converts come to him rather than force conversion on the Chinese. Faith is something one come to out of personal conviction and sincerity. Francis comes in conflict with the church because of his pluralistic viewpoint, that how people treat each other is more important than the particular faith that is embraced. In this way, Keys of the Kingdom is as unusual a film about faith as The Immortal Sergeant undermines itself as a war film. In The Keys of the Kingdom, it is less important to be Catholic or even Christian in one's identity than it is to do good in the world.

Both Fonda and Peck are encouraged by their mentors in the form of voices that they hear from Thomas Mitchell and Edmund Gwenn respectively. That these two idiosyncratic mentors are dead almost suggests that one could almost retitle either of Stahl's films about men with a mission, "Leave Him to Heaven".