You can use a pH indicator to measure some liquids to see whether they are acids or bases. Just like in determining if a solution is an acid or a base, Jesus told us of an indicator to determine if we are his disciples, it is the love God gives us for one another....
The Bible gives us a clear example that Missions is a partnership. It is a team effort of those who go and those who send them out. Missionaries are the deputies of the churches, who go out for them taking the Gospel to the uttermost parts of the earth....