I tend to think that Universalism - the view that God will eventually save all people not condemning any - is probably more widespread than many people suspect. Some move from Calvinism to Universalism because they think if a thoroughly good God monergistically saves people, then he must do that for all. Some Arminians may tend towards Universalism because they emphasize God's love for all people. If God loves everyone, then will he not ultimately save everyone? In this post, I intend to show that Universalism is incompatible with Arminianism. I will do so by highlighting the incoherency of attempting to combine Universalism with one of the primary tenets of Arminianism, namely resistible grace.
Universalism is incompatible with the biblical and Arminian doctrine of resistible grace. To be a Universalist you must believe that God will one day save all people. This means that God will one day have to overcome their resistance to him. If he does not, then theoretically the salvation project could go on infinitely. If God is to save all, and if we are to have any sort of biblical eschatology with bodily resurrection for those who are in Christ, then God must eventually overcome the resistance of those who persist in disobedience and unbelief in order to transform them into the likeness of the resurrected Christ. Even if there is the opportunity for post-mortem salvation (which is unbiblical), these persons could resist forever. God would eventually have to overcome their resistance.
Arminianism holds that grace is resistible. God, by his gracious call in the gospel, enables human beings to respond in faith, but he does not force their conversion. In this sovereignly chosen framework, God will not save everyone. If he did, he would have to break through their resistance and coerce their wills. The Arminian vision of resistible grace is incompatible with Universalism.
So, to answer the question as to why I'm not a Universalist (other than that it seems quite incompatible with scripture), I'm not a Universalist precisely because I'm Arminian. Univeralists must be committed to a Calvinistic model of irresistible grace. I believe with all Arminians that grace is indeed resistible. God will not overcome the wills of those who persist in unbelief. Thus, if there is ever to be a consummation of the kingdom of Heaven, it regrettably cannot include all people who have ever lived.