the problem is in the version of the Bible your reading the actual word is servant not slave
“Bond-slave” arises from the same origin and is a direct (albeit emphatic) synonym to “slave,” again meaning an owned or purchased slave, one bound to a master as opposed to a free person. These words aren’t used today outside of Christianese, which lends them to easier misunderstanding. The translations that use “bond-servant” are actually trying to distance themselves from the KJV, which simply uses “servant,” which isn’t really the right word to translate δοὐλος today, since “servant” in modern English implies a free person in distinction from a slave bound to an owner. But many translations are a bit twitchy about using the word “slave” in these cases due to the extremely negative connotation attached to this word today (thanks to our history of race-based slavery). Thus, some 20th Century translations elected to go with the somewhat archaic but more precise “bondservant” (NKJV & NASB) or “bondslave” (again the NASB, which isn’t consistent w/its rendering of this word).