Is Hitler in Heaven? The Truth About Universalism

Last week, while in a Bible chat room on the internet, another person in the same chat room was affirming Universalism, defined as
a theological doctrine that all human beings will eventually be saved; the principles & practices of a liberal Christian denomination founded in the 18th century originally to uphold the belief in universal salvation and now united with Unitarianism.
(Merriam-Webster.com)
According to Universalism doctrine, all people, no matter what they have done will be redeemed and go to heaven. While in the chat room, I asked the proponent of the doctrine if Adolf Hitler will also be in heaven, to which he earnestly replied “Yes.”