What is the basis for missions in a wider hope/inclusive framework?

I think this question deserves an answer from an LDS (Mormon) perspective, because our doctrine fits the requirements of the question: We have both an inclusivist perspective (at least as I understand your usage of the word inclusivist) and a heavy emphasis on missionary work. I apologize if you want your answer grounded in more traditional Christianity and I'll try to stay in the Bible as much as possible.

That said, I will now answer the question.

First of all, the Bible's pretty clear as to both the importance of missionary work and its intended purpose. The ends of both Matthew (28:19-20) and Mark (16:15-16) come to mind, and I assume you know both passages well. I think most denominations can agree on this.

Secondly, I assume you have experiences with Christianity that have changed you, given you joy, given life meaning, etc. I have as well. I have no source other than what I hear continually in Sunday School lessons, but the LDS perspective here is that if religion has been so transformative for us, then why should we not share it with others? (Actually, I do have a better LDS source: This talk given by Elder Bednar, an apostle, at a recent conference)

With that foundation I can address the idea of inclusivism, which I need to do from a position that is more specifically LDS, because our inclusivism is slightly different from what I've read elsewhere. We interpret 1 Peter 4:6 pretty literally, and in fact Joseph Smith corrects the verse to state that "Because of this, the gospel is preached to them who are dead" (JST, emphasis added). Doctrine and Covenants 138 describes a vision by Joseph F. Smith, 4th president of the Church, regarding this very subject, and it starts by considering both that verse and 1 Peter 3:18-20, which we associate with it. In fact, we believe that through this mechanism of preaching to the dead, literally every person who has ever lived, or who ever will live, will get the chance to hear the Gospel of Christ and decide for him or herself whether to accept or reject it. So not only is salvation a possibility for all, but nobody's moral agency is violated.

(I should here note that the entire LDS concept of baptism for the dead rests on harmonizing this concept with the idea that baptism is essential for salvation, which John 3:5 seems to state explicitly.)

Does the above doctrine absolve us of our missionary responsibilities? Not at all! It simply adds a new dimension to them. We expect to share the gospel with others both in this life and in the life to come.

I beheld that the faithful elders of this dispensation, when they depart from this mortal life, continue their labors in the preaching of the gospel of repentance and redemption, through the sacrifice of the Only Begotten Son of God, among those who are in darkness and under the bondage of sin in the great world of the spirits of the dead. The dead who repent will be redeemed, through obedience to the ordinances of the house of God, and after they have paid the penalty of their transgressions, and are washed clean, shall receive a reward according to their works, for they are heirs of salvation. (Doctrine and Covenants 138:56-58)

I can offer an answer to this question based on the Christian theology of Emanuel Swedenborg (1688-1772) and the denominations that follow his theology. Swedenborg's theology is highly inclusivist: Swedenborg taught that people of all religions can be saved and go to heaven if they believe in God and live a good life according to the teachings of their own religion. (On this subject, see my article: If there's One God, Why All the Different Religions?)

The answer below is extracted and edited from my article, If Non-Christians can Go to Heaven, Why should Christians Evangelize? That article was written in answer to a similar question from a reader. For a more complete version of this answer, please follow the link to the full article.

If Non-Christians can Go to Heaven, Why should Christians Evangelize?

One of the driving forces behind the Christian compulsion to evangelize has been the belief that non-Christians go to hell. Many Christians put tremendous energy into converting non-Christians because they believe that they are doing an eternal favor to all the people they manage to "save" by inducing them to believe in Jesus. That is why they are so persistent.

On the other hand, Christians who believe that non-Christians can go to heaven don't have that driving force compelling them to convert everyone from the corner grocer to major pop stars and sports heroes.

But there are more reasons for evangelizing than simply keeping people out of an eternal hell.

Why did Jesus command us to evangelize?

One reason to evangelize is to spread the good news that the all-powerful God of the universe has become human and present with us as Jesus Christ our Lord.

Think about it.

In the Great Commission, Jesus did not say, "All non-Christians are going to hell. Go therefore and make disciples of all the nations."

No, he said, "All power in heaven and on earth has been given to me. Go therefore and make disciples of all the nations" (Matthew 28:18-19).

Christians who evangelize because they think all non-Christians are going to hell aren't doing it for the reason Jesus Christ commanded us to evangelize.

Jesus Christ commanded us to evangelize because he is God, and he wants everyone to know that. When we know and realize that Jesus Christ has all power in heaven and on earth, we gain access to that power of God so that God can work personally in our lives.

We are not commanded to evangelize those who aren't interested

When Jesus sent out his disciples to evangelize, he told them not to waste their time with those who did not want to hear the message:

Jesus said to them, "Wherever you enter a house, stay there until you leave the place. If any place will not welcome you and they refuse to hear you, as you leave, shake off the dust that is on your feet as a testimony against them." (Mark 6:10–11)

Yes, in other places Jesus had harsh words for those who would not listen to the good news. But notice that he did not tell his disciples to keep trying over and over again to convert those who would not listen. Instead, he told them that when they encountered such people, they should "shake the dust off their feet." Among other things, this means letting those people go and leaving them behind.

To put it in more contemporary terms, our job as Christian evangelists is not to try to convert people who are not interested in the message we're offering.

If people have a religion or a belief that works for them, and they are happy with it, it is not our job to try to change their minds and get them to see things our way.

We are commanded to evangelize those who are confused, searching, hurting, or on the wrong track

Instead, our job is to offer the good news to people who are struggling and seeking answers. We are also commanded to reach out to those who are enslaved to selfish, materialistic, and destructive ways of thinking, feeling, and living. When Jesus sent out his disciples to spread the good news,

They went out and proclaimed that all should repent. They cast out many demons, and anointed with oil many who were sick and cured them. (Mark 6:12–13)

"Repenting" means leaving behind selfish, greedy, and destructive thoughts and actions, and turning our life over to God and goodness instead. And spiritually speaking:

• "Casting out demons" means helping people to overcome inner "demons" such as hopelessness, despair, and a sense of personal worthlessness.
• "Anointing with oil" means offering love, compassion, and concern to those who feel that no one loves them or cares about them.
• "Curing those who are sick" means helping people to overcome the mental sickness of false and crippling beliefs that prevent them from moving forward with their lives.

In short, Jesus commands us to spread the good news to all who are engaged in evil and destructive lives, and to all who are hurt, confused, searching, and in need of God's love, wisdom, and presence.

Jesus has sent us to reach out to people in need of his message and his presence

When we see someone who is hurting, or on the wrong track, or seeking help and answers, Jesus Christ is commanding us to "go and make disciples of all the nations." It doesn't matter who the person is. It doesn't matter what race or nationality. It doesn't matter if it's a man or a woman. It doesn't matter if they're rich and successful or poor and downtrodden.

No matter what someone's situation may be here on earth, we have a message of spiritual good news to offer. It is a healing message. It is a message of comfort and hope. It is a message that can turn people's lives around. It is a message that can bring joy, purpose, and meaning to the lives of those who have only struggles, sorrow, and pain.

That is why Jesus sends us out to make disciples of all the nations. The Lord God Jesus Christ loves every single person on earth. And God has sent us to proclaim that good news to everyone who is in need of it, and has ears to hear it.