1. Unless you are omnipresent, don't you think that Christians do a lot of good things you know nothing about?
2. Christians routinely give more to charity than any other segment of society.
3. Why do you care, and why is it any of your business what someone else does?
This begs the question- what are YOU doing to help the less fortunate? I can give you a list of very good organizations where a larger % of your donations will actually make it those you want to help.
btw- The failings of others will make no difference for you when you stand before God one day. You will answer for what you did when it comes to His Son, Jesus. You will either answer and pay for your own sins, or you will have repented and placed your faith in Christ, thus accepting His payment for your sins.
Whether you end up in Heaven or Hell will have absolutely nothing to do with what someone else did or did not do.