Engage with someone who questions your religious beliefs and argues about theological concepts such as infallibility and the nature of God's commands. Additionally, question their understanding of the subject matter by asking for citations and references.
Excellent, argue definitions, and if necessary, demand citations and references!  Surprised to hear the Church does not teach infallibility.  Are you sure you are a True Catholic, and not one of those cafeteria types.  In any event, we agree, if God  says kill, then babies, pregnant women, whatever, it's OK to kill them.  In His Mercy, of course.