“It is very hard for evil to take hold of the unconsenting soul.”
― Ursula K. Le Guin, A Wizard of Earthsea
People don’t suddenly fall, having their genitals pop out and touch another’s because they tripped while walking down the street minding their own business on the way to do charity work. They got in that compromised position over time, with each little choice that watered the seed of sin in their heart and compromised their integrity.
If there is no enemy inside, no enemy outside can pierce your walls. But if you have darkness inside (which we all do) and do not actively work against it, your fortress of virtue will crumble from within the instant the temptation appears at your door. Maintain the integrity of the walls inside.
Solzhenitsyn famously pointed out that good and evil are separated not by physical borders but in the hearts of people. Keeping the dark desires for control and to harm others behind impenetrable walls requires diligence but must be done to protect the balance of your soul and those you care for. Else your morals and eventually life will crumble as the enemy horde rushes over your life.