Part of being a good steward (manager) of what God has provided is to give a portion back to Him. We pay the tithe, or 10 percent, of whatever we receive from Him. That tithe should be paid on our gross salary. It's not that God needs our money; rather, giving serves as an external, material testimony that God owns both the material and spiritual things of our lives.
The tithe is an indicator of obedience to all of God's laws. He is looking for the right attitude in our giving.
In the Old Testament book of Malachi we're told that God wants us to direct our entire tithe into the storehouse. A storehouse in the Old Testament had four functions. It was used to feed (1) the tribe of Levi and the priests of Aaron, (2) the prophets, (3) the Hebrew widows and orphans living within the city, and (4) the widows and orphans of the Gentiles who were living in and around the Hebrew city.
However, the equivalent of the Old Testament storehouse in the New Testament, as well as in our present day society, is the local church. God's Word tells us to bring our tithes into the storehouse (Malachi 3:10). When we obey Him and pay our tithes to the church, God holds the leaders of the church responsible for the distribution of the tithes (Nehemiah 12:44-45, 13:5,13). If we associate the functions of the Old Testament storehouse with the New Testament and current local church, its fourfold function would be to provide for the needs of (1) the pastor and staff, (2) missionaries and evangelists, (3) widows, orphans, single parents, and invalids in the local church, and (4) the unsaved who surround the local church.
Should we give our tithes to pay for Christian education?
The tithe belongs to God. It's our material testimony that God owns everything in our lives. When we take a portion of our tithe and divert it to keep our children in Christian schools, it's really a gift in self-interest. Educational costs are your normal responsibility. Therefore, if God wants your children to attend private school, He will provide the funds without your having to divert His tithe for that purpose.
Should we give our tithes to secular humanitarian organizations?
Because our tithes are given as a testimony in His name, the ministries that serve in God's name should be the recipients of our tithes. Therefore, the tithe should not be used to support secular organizations. However, that doesn't mean that there are not worthy organizations to which you can give. It simply means that the tithe—the first 10 percent of your gross income—should not be used to support secular organizations.