This song can be seen as being sung to the Holy Spirit who sees everything about us. It could be seen as about a Holy relationship and a mighty companion that just accepts everything about you and doesn't reject you ever.
We cannot go Home alone! As we grow in our relationship with the Holy Spirit, we may seem to draw others towards us who reflect our purpose (forgiveness) back to us. The Course calls these ones "mighty companions" and they truly are pillars of strength because they support the Truth in us.