Paul speaks of this kind of talk as if it were something that could physically move to another location, and he speaks of godlessness as if it were that new location. AT: "which causes people to become more and more ungodly" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Cancer quickly spreads in a person's body and destroys it. This is a metaphor that means what those people were saying would spread from person to person and harm the faith of those who heard it. AT: "What they say will spread like an infectious disease" or "Their talk will spread quickly and cause destruction like cancer" (See: [[rc://en/ta/man/translate/figs-simile]])
Here "gone astray from the truth" is a metaphor for no longer believing or teaching what is true. AT: "who have started saying things that are not true" (See: [[rc://en/ta/man/translate/figs-metaphor]])