In all the wrangling over hell, Rob Bell, universalism and pluralism, it's important that we don't lose site of the issues. One issue is that God is a God who relates to his people by way of covenant. All of God's interactions with his people are by way of covenants: from Adam right on down through Christ.
With covenant you can either be in and out of covenant. So, angels are not under the federal headship of Adam, but all human beings are. Originally only the line of Abraham was under the Abrahamic covenant all though you could join as a proselyte and in the New Testament, Gentiles are grafted in as Christ has fulfilled the covenant. But Gentiles are only grafted in as the profess faith in Christ.
At stake in the issues of pluralism and universalism is not merely a question of who's in and who's out. This is not theologians standing around playing 'einie-meanie-minie-moe'--rather what is at stake is the covenant character of God and this covenant character is the fundamental way by which he exercises his Lordship.
The promised hope of the Bible is: "I will be their God and they will be my people." But this only happens through the covenant union with which he enters into with his people via Christ. Which is why one cannot merely call on God by names other than Christ and God's own covenant names. At stake is not merely a label: as if I call water as root beer, you call it aqua but we both have the same referent. One has to know God by way of covenant and thus one has to have the right person as the object our religious devotion, faith and trust.
In this respect, religious inclusivism is not a nice option that gets us all to heaven:
While political toleration is a benefit for democratic culture, YHWH ranks religious pluralism enemy number one in his stipulations for his covenant people, as enshrined in the Decalogue. The sole lordship of YHWH, as we have seen, is the presupposition of biblical faith, and it is carried forward into fuller revelation of YHWH’s identity as applied to Jesus Christ…God is jealous for his own name and for the people who call on his name and are called by his name. God will not give his glory to another. (Michael Horton, Lord and Servant, 63. In our ellipsis, we have omitted Horton’s quotations of John 14:6; Philippians 2:9-10 and Acts 4:12.)