What is the most important qualification or training need for would be missionaries?
Well, you could look at some mission agency websites to find out, or perhaps a missionary training college might have some thoughts. Then again, controversially perhaps, you could look at the Bible! The end of Matthew 28 (sometimes called the Great Commission) gives Jesus call to mission for his disciples
Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age.
As we’ve discussed previously, this passage only contains one command in Greek, the command to make disciples. The going, baptising and teaching are subsidiary to this main command. So then, mission is fundamentally about making disciples. This means that we can’t content ourselves with evangelism (making converts) or social action – though these things are important. We must think in terms of making disciples and one way that we will know we have succeeded is when they (in turn) go on to make other disciples. Disciples make disciples.
What this means is that the most important qualification for missionaries is that they are themselves disciples. Training in cross-cultural evangelism, language learning and what have you is important, but on their own these things won’t do. No amount of academic training, however good and appropriate it is, will make up for a lack of basic discipleship.
The important thing to note is that discipleship is developed within the life of the church. It is as we learn to serve, to worship and pray together and to grow in the basic disciplines (the clue is in the word) of the Christian life that we develop the sort of discipleship that will allow us to go on to make disciples in turn. The role of the training college is to add specialist skills and knowledge to the discipleship that is already there.