How does one know who are new members?

Some new members may be Sock Puppets.

The best way to get to know who the new members are is to follow their posts and observe how they treat others in the forums. Of course, this acquainting process may take a few months. After a while you should be able to discern the phony from the genuine.

Unless they use a proxy their IP address would show similar to other accounts they have here.

I use a proxy because I also use my phone at work. Business is business. Personal is personal.

This site is a welcome break from the stress of work during breaks.

P.S Is it usual to have new members arrive who are clearly not of our faith, and seem to want to instigate conflict?

Thanks all

There are always a few who are opinionated, holier than thou, types trying to impress the long-time members of their superior spiritual intellect. Their main goal is to cause dissension and strife. These types are commonly called trolls. They usually don't last very long before being banned or quitting the site out of frustration because the other members aren't buying into their games.

Can't say that's too common anymore.
But people of any belief system Are welcome on the site (per the site owner) long as they aren't promoting other beliefs.
I actually find most troublemakers claim to be Christians, many have been here for a while.

On certain topics, I think certain people get "triggered", for want of a better word.

I've seen otherwise sensible Christians (of the heliocentric theory persuasion) get quite animated and personal when debating the shape of the Earth. I don't think it's really that they're troublemakers, it's just that (unknowingly perhaps) certain non-essential beliefs are so treasured for them, these beliefs become the "hill for them to die on".