There was a tithing thread not long ago, I can't find it. There were pro's and con's.
The biggest argument against was that it is in the OT only.
One of the ministers I watch on occasion was discussing it today. He said:
It is in the NT....Mathew 23:23.
It was a good thread so maybe those against tithing would like to reply to this added info?
Matthew 23:23 New International Version (NIV)
23 “Woe to you, teachers of the law and Pharisees, you hypocrites! You give a tenth of your spices—mint, dill and cumin. But you have neglected the more important matters of the law—justice, mercy and faithfulness. You should have practiced the latter, without neglecting the former.
It's not "in" the NT - Jesus mentioned it on one occasion, when talking to Pharisees who rejected the Messiah and kept their law.
Neither Jesus nor the early church taught that Gentile converts had to tithe - the NT example is that believers gave everything, Acts of the Apostles 2:45, and Paul said that people should give as they have decided and not under compulsion, 2 Corinthians 9:7.
If someone is arguing that tithing is taught in the Bible and therefore should be obeyed, then they should obey it
as it is taught.
That means taking 10% of their crops to Jerusalem, or another place where the Lord has put his name, and eating it there, in the presence of the Lord. Every 3 years, all the tithes from that year's produce should be stored, so that the Levites, who have no allotments, and the poor, and foreigners, may also eat it, Deuteronomy 14:22-29.
The only time that money should be involved is if 10% of your crops is much too heavy for you to carry to Jerusalem. Then, you can sell that 10%, carry the money to Jerusalem, buy food with that money and eat that food, Deuteronomy 14:24-26.
But I have never seen this taught.
Tithing, these days, is "you must give 10% of your income to the church" - usually to maintain buildings and pay wages - "because the Bible teaches tithing."
The Bible does not say that, and, imo, it is incorrect to teach that giving 10% of your wages is the same as OT tithing.
The NT teaching is that everything we have comes from the Lord and we should give as he directs us to give.