I see some people’s reactions when it is time to offer their substance to God and wonder if they know whom they are offering it to at all. God isn't poor and He isn't a beggar. He does not need your money. We see in Haggai 2:8 that silver and gold are God's own, If you have the chance to give God an offering, you should do so rejoicing.
Just imaging having an opportunity to meet one of the richest men in the world at a restaurant and he asked that you help pay for the meal he ate because his wallet is not with him, with a promise to repay you. Would you give the money to that man grudgingly?. You know he isn't requesting money because he is poor; for sure, he would repay your money and he is most likely to add some extra.
In fact, in some cases you may not even be interested in getting the money back, you might just see it as a privilege that you had an opportunity to give to the rich man. In this manner, why then do you treat God like a beggar when requested to give an offering?.
If you choose to never give offerings or tithes again, I can assure you that the work of God will still continue. When Elijah went to the widow of Zarephath and requested her for a meal, it wasn't Elijah who was in for food, it was the poor widow.
In (1 Kings 19) we can see that an angel brought food and water to Elijah. So, there was nothing preventing the angel from giving him food and water every day; but God sent Elijah to her in the light of the fact that He wanted to meet her need.
The Almighty God owns everything on earth. If God asks you to give Him something, no for sure that it is because He wants to bless you. I hope your reaction towards giving to God will change from now.