Parshas Nitzavim:
??????? ??????? ??? ?????? ????????(the wood choppers and water drawers).The gemara in yevamos(79) explains that these people where from giveon who converted. The question is, how can they convert if in the same mesechta it says that a convert needs mila,mikveh,and accepting all the mitzvos,but they where in the midbar and were exempt from mila(it was a sakana). There is a gemara in yoma which explains that it is better to live and do many mitzvos then to die doing one. Given this reason we can now understand how they converted in the midbar. A jew can perform all mitzvos,but a goy cannot until they convert. So a goy can technically take the risk of dying to perform one mitzvah of mila since without mila they cant perform any.(Panim Yafos)
Look how great and powerful one mitzvah is.