The answer
I am pleased to hear your Sunday school class desires to serve those who are less fortunate.Although the motive is a charitable one, buying and selling to meet this end is not. This is the same as commercialism. If people desire to give of their means to support poor orphans, which is an obedience to God’s command, then they should do so from their hearts and means without waiting for a return.
In the Holy Gospel of St. Luke 19:45-46 tells a very familiar story about the Lord Jesus Christ cleansing the Temple from this very thing. "Then He went into the temple and began to drive out those who bought and sold in it, saying to them 'It is written, My house is a house of prayer, but you have made it a den of thieves."
The temple area was where the selling and buying of animals for sacrifices took place; and although it was regulated by the Law, the Lord thought the atmosphere as an inappropriate one for the temple. It has been thought by many that this act by the Lord Jesus Christ marks the beginning of His death plot by the opposers of His teachings.
In God’s house, money should not be exchanged for any reason whatsoever. Even books should not be sold for higher than their cost (not even for the smallest of profits) for the sake of covering church expenses or to benefit other church functions.
Donations should come from the heart and be just donated.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)