Do cultures rise and fall with their religions?

Western civilization has been running out of steam for some time now and is obviously in a decadent phase; the phenomena corresponds to the advent in Europe of secularization. More locally,in the U.S. even by 1980 it was sufficiently obvious that we were as a nation becoming deflated and directionless that President Carter found it necessary to address the issue in his "National Malaise" speech. These days we seem to be standing still,except for technology. Since we all know the fate of past cultures - first,the death of faith,then the death of culture - and we all can see the same arc with Christianity,the peak of it's influence correlating to the peak of European culture - the Renaissance - shouldn't there be more concern? Or do we let it all happen?