Thomas Talbott has written a simple argument for Universalism based on the power of love to link the emotional state of each us to that of others. On the Reasonable Faith Forum, I have presented a syllogism of the argument, reproduced below.
Premise 1: If not all people get to Heaven, Heaven would be a place of sadness.
Premise 2: Heaven is not a place of sadness.
Conclusion: All people get to Heaven.
This argument can also be used not only to establish that all people get to Heaven, but also to establish that nobody has been forced to get there, as follows. The conclusion of the argument establishes that all people are in Heaven. And because Heaven is not a place of sadness (Premise 2), all people there have freely chosen to be there, for if any of them had freely chosen not to be there, Heaven would be a place of sadness for them. Consequently, nobody in Heaven has been forced to be there against his or her free will. All people have freely chosen to be there.