For the most part, it's passport control first..then you retrieve luggage (luggage claim)..then customs! Wouldn't worry much about someone grabbing your luggage..as mentioned, by the time you go through passport control, chances are you'll still be waiting for your luggage once you get to baggage claim!
Do you get luggage before clearing customs?
Generally speaking, you collect your luggage after immigration (passport) control, but before customs control. However, if you are a transit passenger, you may not have to collect your baggage at all. This depends on which airport/country you are passing through and whether or not a change of airline is involved.