How is sin still being equated with free will, when we don't even know whether we live in a world with free will?
Say the world was like Newton believed: everything going like clockwork, with nothing happening that wasn't planned. People would still be doing sinful things, as defined by the Bible; yet, there would be no free will.
When Luk says "free will" he actually means "human", because, as we know, animals can't sin, because they have no free will. (circular definition)
There are some types of "sin" that I can think of
(1) individual survival: here an individual steals food off another, so he can survive. This is defined as a sin by the Bible, but animals have no problem doing it. Stealing can make life easier for the animal/person that does it.
(2) stimulatory decadence: person gets hooked on drugs and drags their girlfriend into it. He then lives with dope addicts, surrounded by stolen parts, and melodramatic people sleeping in his hallway, stealing his stuff. Cool lifestyle, bro.
(3) optional psychopathic sin: person just decides to kill his neighbour, or steal funds from retirement fund, for kicks
So, you can see that some sin makes your life easier, and some sin makes your life harder. Screw around and get HIV; your life gets harder. Behave like a suburban square and play by the rules, never give money to charity, then your life gets easier.
The types of sin that we are compelled to do, because we need to survive, are things where we have diminished freedom. Jesus says "give all your money away", but nobody does, because it's idiotic. We don't have the free will do do what he says, because the system will make it difficult for us. Jesus says don't think about food, yet every animal has to think about food, or it dies. Some can elect to be vegetarian, because they regard killing animals as a sin. However, most humans are probably compelled to commit this sin, due to lack of freedom. We are born to sin in this way, just as we like jerking off and screwing around.
Another thing which diminishes freedom is a brain tumour, that makes you so bad tempered that you want to shoot kids in school. When a child does that, he is a deemed an evil sinner, but when a brain scan shows a tumour, everyone suddenly understands that he had diminished freedom. Then he's a poor victim.
The reason Christianity likes the words "free will", is that it's all about blame. The religion just doesn't work without people blaming and judging, being neurotic and guilty.
You cannot prove whether or not we live in a deterministic universe with no free will, and even if we lived in one where events could be random, the deck is still stacked against us, because of diminished freedom.
Christianity likes to pretend that the guy in the wheelchair with allergies, had the freedom to get healed and give his money away and go help people in Africa, because keeping that dream alive helps people be in a perpetual state of guilt.
BLAME: that's all it's about.
Define humans to have free will, without showing any evidence or examining what it really is, and then say "you chose to go to hell - not God's fault". END OF STORY.