In any religion people may experience profound transformation, love or God, whatever you want to call it. And then they confuse that with the silly details. The silly details must be true also. But God is always available, religion or not. You don't have to wear the special underwear, get baptized or bar mitzvahed or pray with beads. But when people have this experience of God, they think they've found the true religion and drink the koolaid. But they were wrong for assuming there was a correct religion in the first place. Man makes up stuff like ritual and tithing and abstaining from shellfish or coffee.
No, more people should not believe in Universalism, because to believe in Universalism is only to believe in nothing. People who believe in Universalism believe that anything goes. They believe that there is nothing that is better than another thing. This is truly a belief in nothing, except for the lowest common denominator for anything. More people believing in that would not be helpful.
I am a firm believer that only one truth can be true. If I got in a car wreck and there were eight witnesses, but each witness told a completely different story, they cannot possibly all be true. So then, how can you say that everyone's faith or beliefs will earn them the right to heaven? If one belief is true and the opposite belief is also true, how can they both be true? I am particularly hard on Christians who believe that Universalism is true, because you didn't even read the Bible. John 14:6, Jesus proclaims that He is THE way. Not A way, but THE way. As in THE ONLY way. Therefore, Universalism is not true, which classifies it as a heresy.
No. While I'm an atheist, I understand that more people do require something to believe in. For some people, that requirement gets very specific with regard to religion, what type of religion, what specific god or prophet they follow, dietary rules, and so on. Some people have a more general attitude for it, and good for them, but like any other religious viewpoint, it doesn't need the help of evangelism.
People should believe what they want and the theory of Universalism is no different. I have issues with universalism because, as a follower of the Bible, I have been taught that not everyone is going to go to Heaven. We are all sinners and none of us are worthy of God's grace, however, it is there for acceptance if we are so inclined to grab and hold onto it. Universalism teaches that people can do whatever they want and will still be forgiven by God's grace. We are only forgiven if we are truly repentant and take it upon ourselves to ask for forgiveness.
The hardest task that has been undertaken by social scientists is trying to establish a common set of X for a given subject, Y. Ultimately, its far easier to believe that culture is mutable over time/space, and that, rather than there being a core set of values everyone implicitly recognizes, that people are different.
I don't think that more people should believe in Universalism, unless they want to. It is a nice belief, and a lot better than many beliefs out there. It would be nice if more people believed that everything is connected, etc... But I don't think they SHOULD believe, they can believe whatever they want.