It is not about slavery but choice.
It is you who define it as slavery, I never used such a word.
The reality is everyone want to live. It is a #1 desire.
And in order to stay alive you need to buy your meal and a roof above you.
Under pure “capitalism” as they call it you have to engage in enterprise or sell your labor to have your meal and shelter.
If you aren’t you are about to have no meal and home and you’ll die.
That is how free market naturally forces you to work.
And if you want to improve your conditions you have to double or tripple your efforts. It is both how economic growth and living conditions improves under free market.
None of the above really work under communism and it’s soft forms.
That is marxism explained in it’s own terms.
I actually feel comfortable with the way capitalism “forces” people to work.
Unlike marxism it doesn’t need work camps and comissars at some point to herd demoralized people who lost connection between free stuff on one side and labor&enterprise on the other side.
Forced labor (save for genuine criminals, many of whom probably ought to receive capital punishment anyhow) is slave labor. Unforced labor is not. It really is not hard to define, unless all labor is somehow “forced” (which it isn’t).
I see you are defining “pure capitalism” in communists’ terms. Automatic false dilemma. There are other ways to subsist than being part of an enterprise or having to sell labor to those who can afford to buy it.
And besides, I was not speaking of the capital/labor aspects of communism when I first replied to this thread, but rather the (doctrinal) rejection of religion by communists.