There are two flavors of universalism. Christian universalism says that that God through the death and resurrection of Jesus Christ wills the eventual saving of all peoples, believers and nonbelievers alike. Because God wills this future for all of us, it will happen, in this earthly life or the timelessness of eternity.
God
universalism says that God is not a dictator pulling strings in our world but
is hidden among us working for the eventual union of all peoples with God. God
would not be God if what God wills is only a future for the few. Our beginning
was created by God and we all shall one day be a part of the God willed eternal
future.
God only for
the few is the Christian theological tradition. St. Augustine started this
heaven and hell tradition some four hundred years after Jesus walked among us.
From time to time other theologians have done some fine tuning but the gist of
this God thinking has stood in place as the predominate understanding about
God.