Is it not true, that the most we can do is make the clean to become unclean?

Haggai 2:12 If one bear holy flesh in the skirt of his garment, and with his skirt do touch bread, or pottage, or wine, or oil, or any meat, shall it be holy? And the priests answered and said, No.
 13 Then said Haggai, If one that is unclean by a dead body touch any of these, shall it be unclean? And the priests answered and said, It shall be unclean.

However, cannot Jesus make the unclean to become clean?

Matthew 8:2And, behold, there came a leper and worshipped him, saying, Lord, if thou wilt, thou canst make me clean.
 3 And Jesus put forth his hand, and touched him, saying, I will; be thou clean. And immediately his leprosy was cleansed.
   Is the Jesus healing the leper a sign, a picture of how he makes an unclean soul to become clean?