Tithing is essentially acknowledging God for giving you your money in the first place.

God is clearly challenging us to tithe.

Bring ye all the tithes into the storehouse, that there may be meat in mine house, and prove me now herewith, saith the Lord of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough to receive it.
- Malachi 3:10 (KJV)

The phrase "prove me now herewith" means something like "put me to the test". That's about the only time God tells people to test Him. I find that really interesting.

I've spoken with people that found it hard to tithe to the church, simply because they didn't like the way the church was spending it. Fair enough.

If you struggle with that, you can always give the money directly to the poor. (Bypassing the middle man if you will)

Sell that ye have, and give alms; provide yourselves bags which wax not old, a treasure in the heavens that faileth not, where no thief approacheth, neither moth corrupteth.
- Luke 12:33 (KJV)

Life here on Earth is temporary. What good is it when you have lots of money while you ignore people in need.

And the King shall answer and say unto them, Verily I say unto you, Inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me.
- Matthew 25:40 (KJV)