Evil and good cannot coexist; the more evil is removed, the more good is focused on and felt. This is the case because all who are in the spiritual world have a field of their particular love emanating around them. This field spreads all around and has an effect on others. It creates feelings of harmony or antipathy. These fields separate the good from the evil.
The fact that evil has to be removed before goodness is recognized, perceived, and loved could be compared with many situations that are possible in our world; for example, the following: Suppose someone keeps a leopard and a panther in an apartment and, as the one who feeds them, is able to live safely with them. No one else can visit unless their owner first removes these wild animals.
Guests invited to the table of the king and queen would not forget to wash their faces and hands before attending. No bridegroom goes into the bedroom with his bride after the wedding without first washing himself all over and putting on aa wedding garment. Anyone must first purify one with fire and remove slag before getting pure gold or silver. Everyone separates the tares or weeds from the harvested wheat before taking it into the barn. Everyone removes the beards from harvested barley with threshing tools before bringing it home.
Everyone cooks some of the juice out of raw meat before it becomes edible and is set on the table. Everyone knocks the grubs and caterpillars off the leaves of trees in the garden to prevent them from devouring the leaves and causing a loss of fruit. Everyone removes garbage from the house and the front entrance and cleans up those areas, especially when expecting a visit from a prince or the prince’s daughter to whom one is engaged. Does any man love a young woman and propose to marry her if she is riddled with malignancies or covered all over with pustules and varicose veins, no matter how much she puts makeup on her face, wears gorgeous clothing, and makes an effort to be attractive by saying nice things and paying compliments?
The need for us to purify yourselves from evils, and not to wait for the Lord to do it without our participation, is like a servant coming in with his face and clothes covered in soot and dung, approaching his master, and saying, “Lord, wash me.” Surely his master would tell him, “You foolish servant! What are you saying? Look, there is the water, soap, and a towel. Don’t you have hands? Don’t they work? Wash yourself!”
The Lord God is going to say, “The means of being purified come from me. Your willingness and power come from me. Therefore use these gifts and endowments of mine as your own and you will be purified.” And so on.
The need for the outer self to be cleansed, but to be cleansed through the inner self, is something that the Lord teaches in Matthew chapter 23 from beginning to end.
from True Christianity, Section 331