But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, they shall have their portion in the pool burning with fire and brimstone, which is the second death.
That helps us see that it’s addressing those who “fear” living their faith. Not fear that their faith may bring persecution but fear ever talking about their faith because it’s uncomfortable.
Note, this is different than not wanting to prostelize, and would likely be those who fear answering “yes” to being a Catholic.
Here’s a good example. My very liberal co-workers decided they wanted to get married in the church and I told them about a good Pre-cana. At lunch, in mixed company, they began to laugh at NFP. Even though I could answer some of the things, I directed them to speak to the teachers because I feel that discussing periods, libido and sex in mixed company is tasteless, no matter how “progressive” our society is. So, in short, it is not wrong to act in prudence. But it would have been cowardly for me to join in them laughing at NFP.