Can I use liquid sandpaper instead of sanding when refinishing my 70's kitchen cabinets?

My kitchen cabinets are from the 70's--clear birch with varnish or polyurethane over. I want to paint over them but would prefer to do it without the mess and hle of sanding. How effective would liquid sandpaper be in this situation? I have been told I need to sand, primer with an oil-based paint, then paint. Any suggestions?