Is there a calling such as an apologist in the Bible? Any example of an apologist among the apostles/disciples?
Apologetics comes from the word apologia in 1 Peter 3:15 which Magenta quoted above.
It's directly from the Bible.
All Christians are told to do this, but historically we seem to always find people who are especially gifted for it.
It doesn't necessarily need to be separated from traditional ministry, but there does seem to be an extreme need for apologetics in the modern world. As attacks on Christianity become more and more brutal from the world of secularism and secular science, there seems to have naturally arisen a number of Christians who are especially gifted to answer these attacks.
These people seem to be naturally filling a need within the body of Christ.
The Bible does not specifically call for individuals to "specialize" in apologetics, but in the modern world, and under the current attacks from secularism, there does seem to be a genuine need for people to specialize in it... a need which seems to be naturally filled by men who seem especially gifted for it.
So, there is this thing called apologia which God tells all of us to do.
There seems to be a need for some people to be especially gifted at it,
and God seems to have raised up people to fill this need...
just as he has raised up people to fill needs in many kinds of ministry,
and in many vocations.
It's not mysterious.