For them, tolerance is the belief that all religions are paths to salvation. But even if pluralists agree that Christianity is just one path to salvation among many, they disagree with Christianity's claim that it is the one true religion. On this count, they believe Christians in fact to be wrong. That occasions true tolerance. All religions, whether pluralistic or exclusivist, claim to be right in some respect in which others are wrong.
Pluralism claims that the exclusivity of some religions is wrong.
Pluralists would have all people somehow be true to themselves, keeping their own religious traditions. But when a religious tradition indicates that it is the only way to salvation, it must discard that part of its belief system. Ecumenism celebrates religious belief in the abstract. And that is the puzzle. Without making a judgment on the truth of any particular religion, if a religion believed that I, as a non-believer, was in danger of the fires of Hell, I would find it natural for them to share their message with me.