Zeleste,
Justifing or making excuses why you should not tithe, you never have and never will I believe is what you stated before. No Body is trying to guilt you into giving to your local Church. The idea behind tithing is giving back to God but not just with money but with your time. So you don't Tithe how much time do you take out for the Lord each week, to pray, Fast, and read his word? We all have Mortgages, or rent families and survival is tuff, but God expects us as Christians to take time out for him, if you are eating daily, how is your spiritual life are you eating daily or are you starving?
Many people are dealing with the economy lack of Jobs and cut backs. God knows your situation, and what you need before you ask but he still wants you to ask. I do tithe myself and I find nothing wrong with it in fact, I have been Blessed, and lack for nothing. God has provided all of my families needs, now if this has not happened to you, I don't know what to tell you? that is a individual response between you and God. I will say this God has never let me down, as long as you follow the Bible you will not go wrong.