What is the significance of the fire imagery used to describe Mildred and her friends in the Sieve and the Sand?

Montag, himself "on fire" after talking to Faber, comes home to find Millie and her friends watching the White Cartoon Clowns on the view screens. He turns off the television and definitely spoils the party. He looks at the women, and they remind him of the plaster statues of saints he used to see in church. He would try to feel some emotion about the dead statues and about religion, but it seemed alien to him. So too do these women. However, as he watches them, he thinks of lighting them up:

So it was now, in his own parlour, with these women twisting in their chairs under his gaze, lighting cigarettes, blowing smoke, touching their sun-fired hair and examining their blazing fingernails as if they had caught fire from his look. Their faces grew haunted with silence. They leaned forward at the sound of Montag's swallowing his final bite of food. They listened to his feverish breathing.

What Montag is doing here is projecting his own fiery emotions, his own desire to change his society and go deeper, onto them. It is his emotional upheaval and inner turmoil, almost a frenzy, that causes their hair and nails to look as though they're on fire. It is under his "gaze" that they are lit, as if they "had caught fire from his look." It is his breathing that is feverish or hot. They are like ghosts, "haunted" by the silence of having no view screens on, but he wishes to spread his fire—his passion—to them. They represent the meaningless, superficial, emotionally dead society he would like to transform. Montag has gone from wanting to burn books to wanting to light people up with the passion of his convictions.