Matthew 6: 19 Lay not up for yourselves treasures upon earth, where moth and rust doth corrupt, and where thieves break through and steal: 20 But lay up for yourselves treasures in heaven, where neither moth nor rust doth corrupt, and where thieves do not break through nor steal: 21 For where your treasure is, there will your heart be also. 22 The light of the body is the eye: if therefore thine eye be single, thy whole body shall be full of light. 23 But if thine eye be evil, thy whole body shall be full of darkness. If therefore the light that is in thee be darkness, how great is that darkness! 24 No man can serve two masters: for either he will hate the one, and love the other; or else he will hold to the one, and despise the other. Ye cannot serve God and mammon.
We cannot serve both God and mammon. Some men have a darkness in their eyes. I believe this darkness is what is talked about in verse 22. Some men are just utterly dark. Its not a physical light more perceived spiritually.
These can be believers that is brethren, christians. Mammon christians. Watch out for christians who love money.
(I Timothy 6:10 [KJV]) For the love of money is the root of all evil: which while some coveted after, they have erred from the faith, and pierced themselves through with many sorrows.
(Proverbs 28:22 [KJV]) He that hasteth to be rich hath an evil eye, and considereth not that poverty shall come upon him.
How should we deal with those who serve mammon ?
Just like the evil man, we avoid them.