"No Ammonite or Moabite may enter the assembly of the LORD … (v3).  Israelite society was very concerned with boundaries between “clean” and “unclean” to teach people about God’s holiness.  God’s house (the assembly) had to be protected against the pollution of sin, including groups that represented rebellion (Moabites).  Then Jesus came, bringing forgiveness and purification with him, so that the lame, the blind, women and men, foreigners, and sinners of every kind, could “enter the assembly” of God by faith in him. 

“Because the LORD your God walks in the midst of your camp …” (v14).  Jesus came among us not to condemn us, but to forgive and cleanse us, so that we can walk with God in holines