I am a libertarian because I believe in maximizing liberty and minimizing aggression.
I recognize the maximum amount of liberty requires there be no one who can violate liberty free of rightful consequences.
The minimum amount of aggression is zero.
Government is founded on aggression, violations of liberty, and theft.
All externally imposed governments enslave. Slavery is something else I am vehemently against. This means I am an abolitionist.
Slavery is not voluntary. I believe every human interaction should be voluntary, and that when someone tries to force themselves on you, you have a fundamental human right to defend your life, liberty, and property from their advances. This is why I am a Voluntaryist.
I will embrace whichever of these labels for myself I want, for whatever purpose, whenever it suits me. They are interchangeable, unless you mis-define them.