"Woe to you, scribes and Pharisees, hypocrites! For you tithe mint and dill and cumin, and have neglected the weightier matters of the law: justice and mercy and faithfulness. These you ought to have done, without neglecting the others. You blind guides, straining out a gnat and swallowing a camel!" (Matthew 23:23-24)
Here we see Jesus condemning the Pharisees for neglecting weightier matters of the law. The Pharisees tithed a tenth of everything they received. They understood the law from Leviticus 27 about giving a tenth of everything you were given from the Lord. The Pharisees would give a tenth of everything even small garden crops like mint, dill and cumin. Jesus is not condemning them for tithing because he says "these you ought to have done" but rather for their lack of mercy and faithfulness. The Pharisees were all law and no grace.
When religion is your savior obedience to the law becomes your salvation. This was the issue with the Pharisees. Even tithing, which is something good, became a heavy burden because of the weight behind tithing. There was no salvation if they missed giving a tenth of anything. Paul reminds us that God loves a cheerful giver (2 Corinthians 9:7) not a disgruntled, heavy laden giver. In Christ giving is a joy not a burden. We give to our local church and missions because of the weightier matters of the law. We see God's faithfulness to provide so it compels us to be faithful to him in our giving. We see the mercy our God has bestowed upon us so we give to missions so that mercy may spread abroad to every tribe, tongue and nation. Tithing is a response to the gospel not the law.
Grace upon grace,