Thislamp has a GREAT post on tithing and on how it is not really used in a biblical way by churches today. Here is an excerpt from it:
Most of the churches with which I’m most familiar would quickly tell their members and the community at large that they preach the grace of Jesus Christ. Yet beyond this grace are little pockets of works and legalism. If it’s promoted that good standing equals a tithe, this is legalism, plain and simple. If taking on a responsibility within the church such as teaching or some committee position or a role like deacon requires giving at least 10% of one’s income, this is legalism by its very definition. And yet these same churches supposedly believe they promote God’s grace in all areas. Sadly, they do not.
Of course thislamp agrees utterly with giving and the support of the church ministry. I have long held that what is known as stewardship season is really the church coercing someone into ‘tithing’ which is not biblical and goes expressly against 2 Corinthians 9:7.