"How, then, can they call on the one they have not believed in?"
"And how can they believe in the one of whom they have not heard?"
"And how can they hear without someone preaching to them?"
What does cross-cultural missions involve?
That the missionary team learn the language of the people, their culture, understand their worldview, study the language and create an alphabet for it (in case they do not have one), teach the people to read and write in their own language (literacy), translate the Bible from Spanish to the language of the people, do Fundamental Bible Teaching lessons, start teaching until a church is born among them.
And after that, discipleship!
In other words, cross-cultural missions require from the missionary a willingness to dedicate almost his entire life working to reach an ethnic group.
"And how can anyone preach unless they are sent?"
As it is written: “How beautiful are the feet of those who bring good news!”