Your posting: “John 8:34 Jesus answered them, “Truly, truly, I say to you, everyone who practices sin is a slave to sin.”
It is a free will choice to remain in sin and reject God.
Jesus furthers states: “because my word finds no place in you.”
Your comment: “Men have a will, for sure, but it is NOT free.”
Even if you are a slave to sin, a slave can reject sin. One needs to seek God’s truth and not man’s truth.
John 8:32 state “and you will know the truth, and the truth will set you free.’ So the acceptance of Jesus liberates us from the slavery of sin, ignorance and deception CCC2466
Which man cannot do without God.
Hence, man is NOT free.
If he were free, he could do it without God's help.