Chronological context provokes the question, where did THE SEVENTH SEAL come from? The previous Bergman films screened, from CRISIS to SMILES OF A SUMMER'S NIGHT, have all been about sexual and romantic relationships. THE SEVENTH SEAL is a nearly complete break from this. Human relationships are portrayed - a happily married couple with child; a whoring actor and cuckolding blacksmith's wife - but in service of a larger thematic matrix.
Certainly the claim can be made that THE SEVENTH SEAL is about the relationship between Man and God. God, however, is nowhere to be found in the film. It may be more apt to say that THE SEVENTH SEAL is about Humanity's relationship with the idea of God, or Humanity's relationship with Humanity's own desire for God.
Before THE SEVENTH SEAL, Bergman's films almost entirely ignore religion. The most explicit statement on religious matters in any of the previous films - Anna's atheistic outburst in SUMMER INTERLUDE - is the sole memorable mention of the topic. (There's a priest in SUMMER INTERLUDE, but he's not much use to anyone.) THE SEVENTH SEAL revisits the matter from a more mature but no more pious vantage.