“Universalism is a doctrine believed by many that teaches that in the end everybody will be saved, that ultimately the saving plan is universal and God's going to save anybody and in the end everybody is going to heaven and hell will not exist. That's how some people answer the problem of if God loves the whole world then how could He possibly send everybody to hell, except that few that believe. They answer it by saying that, well, in the end He won't do it. In the end His love will prevail and He will save everybody. That's universalism.” (John MacArthur)
Universalism teaches that no person, no matter how much they embrace crass disobedience to God, will be excluded from His redemption. They believe God, the loving Father, will bring all people into conformity with his will, thus saving them from eternal damnation.
Origen, in the 3rd century, speculated on this beyond scriptural warrant. Socinus, in the 16th century, brought a revival of this "doctrine." He argued that because Jesus died, ALL would be forgiven.
In the 1800's, this movement organized in the US. But after much internal debate and contradiction, lost its steam and joined with the Unitarians.
I believe in "universal salvation" - that Jesus Christ died for ALL people, even those who would reject Him. It is a "universal and saving light" Robert Barclay noted. John Wesley wrote of that "prevenient grace" a clarifying teaching that describes the universal character of God's wonderful salvation.
God, in scripture, however, declares that there are moral basis's for salvation and never gives indication that He will set these aside to accommodate those who are impenitent.