The Bible defines tithes and offerings differently than most churches today. In the Bible, a tithe was 10% of certain harvests that the Israelites were to donate to the temple for the use of the priests and Levites. There were actually several tithes which overlapped, resulting in a donation of 23.3% (See Leviticus 27:30; Numbers 18:26; Deuteronomy 14:24). In the New Testament, the church didn't need to care for Jewish priests, Levites, or the Temple, so the tithe was not required.
Are tithes and offerings the same thing? Do Christians have to give tithes and offerings?
Offerings in the Bible were just general donations and sacrifices. They included everything from burnt offerings to atone for sin to gold for the construction of the tabernacle. In the New Testament, offerings were collected from churches to support missionaries, like Paul, and to provide for the church in Jerusalem. While offerings were strongly encouraged (1 Corinthians 16:1-2; Philippians 4:14-19), they were not required (2 Corinthians 11:7-8).
Most churches today use the words "tithes" and "offerings" in a slightly different way. A tithe is a donation of 10% of a church member's income that goes toward the pastor's salary, the church facility, and other expenses. (Many churches ignore the fact that the church is not required to tithe. Others use the 10% as a general guideline of what parishioners should give to cover expenses.) An offering is a donation above and beyond 10% that is usually earmarked for missions, a building fund, the needy, or a parachurch ministry.
Using the words "tithe" and "offering" in such a way is fine as long as we understand what the Bible really teaches about giving. Those whose work is dedicated to spreading the gospel should receive their living from those who benefit from that work (1 Corinthians 9:14). God is the giver of everything we have, and we should obey Him in how we use it (James 1:17). There is no set amount that a Christian should give, but there is a specified attitude: generous and cheerful (2 Corinthians 9:6-8). And our offering is not limited to a fraction of our income; God wants all of us (Romans 12:1).
Christian tithing - What does the Bible say?
When tithing a percentage of my income, should it all go to my home church or can I give some to a Christian ministry?
When tithing a percentage of my income, should it be off the net or the gross?
What does it mean to be a cheerful giver?
Should Christians today give a first fruits offering?
Truth about the Christian Life