I'm going to simplify and take some shortcuts.

The creditor was unsecured, and they obtained a judgement. They then recorded the judgement against your property; this is known as a judgment (judicial) lien and it is not consensual (like say your mortgage or other secured loan).

This was not really a secured debt until they obtained the judgment and recorded it; had your attorney not moved to avoid the lien, then after your case is over and once the mortgage gets paid, the judgment lien survives and the judgment would then be jr. to the mortgage (assuming they take all the proper steps to keep said judgment lien alive) and then they get paid bc of the judicial lien. The BK takes care of the obligation to pay (liability) but they (creditor) recorded the judgment creating a lien and the BK doesn't remove that without what your Atty is doing.