Ah...Paul might seem to contradict himself, and in the same chapter of I Corinthians. Read the entire chapter, though, and you'll see that there is no contradiction.
Paul doesn't forbid glossolalia...he merely says that it is not required of Christians. There is a big difference.
Some denominations believe that glossolalia is proof of salvation. Others dismiss it as nonsense. Paul, on the other hand, admits that it is a valid expression, but not required of Christians.
Quoting out of contex is rarely useful.
First Corinthians 14:5 is often quoted to prove that the gift of tongues is still operative today: "Now I wish that you all spoke in tongues, but even more that you would prophesy; and greater is one who prophesies than one who speaks in tongues, unless he interprets, so that the church may receive edifying." Why do some put the emphasis on tongues when Paul said that he had a greater desire for the people to prophesy? I do not have anyone coming around to my door saying that I need to get the gift of prophecy, but I have people praying that I will get the gift of tongues. Paul is saying that he would like them to have all the gifts, but he would rather that they have the greater gifts. Paul is not saying that tongues is the gift they should have. If they should have any, it should be the greater gift of prophecy. The gift of tongues was the least important of all the spiritual gifts. It was last on the list (see 1 Cor. 12:28).