In writing to Believers in the book of Romans, God (through Paul) informs us that "..though [they] were slaves of sin, yet [they] obeyed from the heart that form of doctrine to which you were delivered. And having been set free from sin, you became slaves of righteousness." (Rom.6:17,18; NKJV).
So... although the Lord did actually "...set free from sin..." all true believers, yet as the Apostle John points out in 1Jno.1, we all (including John) still have the capacity to sin.
However... as the passage in Romans shows us, it is not mandatory that we sin. Just as with mankind's freedom to accept God's free gift of salvation or reject it, so we choose; sometimes out of long ingrained habit...whether or not to sin. But... Praise the Lord... He has made provision for our failures in 1John 1:9.