"All these are the work of one and the same Spirit, and he gives them to each one, just as he determines." NIV translation
Once again, Paul makes the point that all of these methods are from the Holy Spirit. We also see that they are given to whoever God desires to have them. This should silence those who would condemn other believers for not displaying the same method (such as the speaking in tongues). We must remember that their purpose is to draw the church together and not separate believers.
"The body is a unit, though it is made up of many parts; and though all its parts are many, they form one body. So it is with Christ. For we were all baptized by one Spirit into one body - whether Jews or Greeks, slave or free - and we were all given the one Spirit to drink." NIV translation
Now, Paul continues to teach on unity as he compares the church (spiritual body of Christ on the earth) with the physical body of a man. As with the human body, the parts of the church must work together to complete its task. There is only one body of Christ on the earth and we all became a part of that body in the same way.
"Now the body is not made up of one part but of many. If the foot should say, 'Because I am not a hand, I do not belong to the body,' it would not for that reason cease to be part of the body. And if an ear should say, 'Because I am not an eye, I do not belong to the body,' it would not for that reason cease to be part of the body. If the whole body were an eye, where would the sense of hearing be? If the whole body were an ear, where would the sense of smell be? But in fact God has arranged the parts in the body, every one of them, just as he wanted them to be. If they were all one part, where would the body be? As it is, there are many parts, but one body." NIV translation
Paul uses the human body as an example to show how ridiculous it is for Christians to be jealous of each other and not work together. In the extreme examples that he gives, the body would not be able to get much accomplished and it is the same way with the church. The body of Christ is to be united by the Spirit and then each part can fulfill its function.
In this case the church would be healthy and get things done. Paul also makes an effort to make us see that every part is significant and that goes for people in the church as well. Every Christian has been given at least one gift that is to be used to build up the church.
"The eye cannot say to the hand, 'I don't need you!' And the head cannot say to the feet, 'I don't need you!' On the contrary, those parts of the body that seem to be weaker are indispensable and the parts that we think are less honorable we treat with special honor. And the parts that are unpresentable are treated with special modesty, while our presentable parts need no special treatment." NIV translation
Paul uses the examples of the hand and the feet to demonstrate the fact that the parts must work together. He goes on to say that the parts that do their job without being seen are just as necessary as the parts that are seen in public. It is the same in the church as some are called to be out front teaching and preaching while others are feeding the hungry and doing other such things.