Does Christianity recommend learning other languages or dealing with non-christians?

Most Christian denominations accept, at least in some part, the teaching of what we call The Great Commission. There are many proof verses for this, but one of the most common is this:

Matthew 28:18 And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. 19 Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: 20 Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen.

Even apart from that, one of the central teachings of Christianity is that salvation is available to the Gentiles, as well as Jews. Paul, the author of the majority of the New Testament books, was very passionate about reaching the Gentiles. The book Acts of the Apostles chronicles the growth of the church after the Resurrection, and much of it deals with journeys abroad to bring the Gospel (good news) to all people.

In practice, much of Christianity has revolved around missionary journeys to far countries for the purpose of sharing the good news of salvation.

As for languages, in practice, many Christians have learned languages for the purpose of spreading the Gospel. However, there are no verses I am familiar with which specifically instruct people to learn other languages.

It may be of note that it was our God who created the language barrier at the Tower of Babel (Genesis 11). He did so because the natural man when working together only find wicked things to do.

However, our God has also given many the "gift of tongues", which allow believers to be able to speak in other languages. In the book of Acts chapter 2, God gives the believers the ability to speak so that when the people from various nations heard them, those people all heard in their own languages.

6 Now when this was noised abroad, the multitude came together, and were confounded, because that every man heard them speak in his own language. 7 And they were all amazed and marvelled, saying one to another, Behold, are not all these which speak Galilaeans? 8 And how hear we every man in our own tongue, wherein we were born? 9 Parthians, and Medes, and Elamites, and the dwellers in Mesopotamia, and in Judaea, and Cappadocia, in Pontus, and Asia, 10 Phrygia, and Pamphylia, in Egypt, and in the parts of Libya about Cyrene, and strangers of Rome, Jews and proselytes, 11 Cretes and Arabians, we do hear them speak in our tongues the wonderful works of God.

There is still a fair amount of debate among denominations on what exactly the gift of tongues is, but we know from that passage that at least God had given such a gift of languages to people.

Paul speaks highly of the gift of tongues in 1 Corinthians chapter 12, but then in chapter 13, uses that as an example to say that even if he spoke very eloquently, the more valuable gift is love. Then, in chapter 14, he proceeds to explain how the gift should be used.

The point I gather from this is that God is very interested in people hearing the Gospel, and He is so interested that if people could hear no other way, he would provide the translation Himself. The main purpose is not simply to talk, but to show love, and more importantly, the good news of salvation from the death and resurrection of Christ. That is the most love we can show, and that is the motivation of so many Christians giving up their lives to not only visit other countries, but to give up their lives to live with the people to love them.

To quote Hudson Taylor, a famous missionary:

If I had a thousand pounds China should have it—if I had a thousand lives, China should have them. No! Not China, but Christ. Can we do too much for Him? Can we do enough for such a precious Saviour?