There is the American Red Cross, for example, and the United Way. I have mentioned before in this space the group Oxfam America, which feeds the hungry and tries to show those in need how to help themselves. The Salvation Army, the Union Rescue Mission, the Los Angeles Mission — all these are groups that seek to feed the hungry and shelter the homeless. All these groups also ask for money, so those of us who attempt to tithe (that's 10% of one's income) may give to some of these groups as well as to our houses of worship.
So if church giving is down, that fact may not be a bad thing. There are scads of good causes out there, and each of us, religious or not, must decide how we want our charity spent.
Jesus said one time, "Whoever is not for us is against us." But he also said, "Whoever is not against us is for us."