It means that to follow Christ requires the faith that is willing to be put to death by men who want to kill you for being a Christian. But if that happens don't be afraid of these men who only have power to kill your body and after that there is nothing that they can do.
If you are dealing with the real fear that would be involved when they told them, "Deny Christ and you can go home, otherwise we are going to feed you to the Lions in the Coliseum on Saturday" Remember that you should not fear them, they can only kill the Body, but you will live forever. However if you deny Christ, you are facing something far worse, eternal hell. Fear Him in that moment and deny your desire to save your body. Let the Fear of the Judge who is able to cast into hell, help you make the right decision in that moment when your "love for Him" might need some additional help. Because He is not going to say "you meant well, you get a pass." And when you realize that, it is a healthy and positive Fear that keeps you on the straight and narrow path.
I want to serve God out of Love but I also know that if I don't there is a hell waiting. That is a big motivator in overcoming temptations and compromise. In my opinion not having this fear of hell is why so many "christians" are doing things that shock me. They think they are not going to have to answer for it. And I recall the words of Jesus...
He said to them,
24“Make every effort to enter through the narrow door,
a because I tell you, many will try to enter and won’t be able
25once the homeowner gets up and shuts the door.
a Then you will stand outside and knock on the door, saying, ‘Lord, open up for us! ’ He will answer you, ‘I don’t know you or where you’re from.’
26Then you will say, ‘We ate and drank in your presence, and you taught in our streets.’
27But he will say, ‘I tell you, I don’t know you or where you’re from. Get away from me,
a all you evildoers! ’
28There will be weeping and gnashing of teeth
a in that place,...
He says "I don't know where you're from" This results in weeping and gnashing of teeth. I fear that enough to say no to sins, backslidings, and compromise.
Don't you?