Oh, come on! Are you being deliberately obtuse? Context! You can't cherry-pick verses and come up with sound doctrine! In order to understand scripture, you must first understand the context. Especially with Paul's writings, they are letters, and he introduces a thought, expands on it, answers objections to it, then restates the original thought with the expanded meaning. He may touch on other doctrines along the way, but his statements on those other doctrines do not cover the whole doctrine, only a point or two of it. That is why you can't build sound doctrine from only one or two scriptures if there are many others which also deal with the same thing.
Another thing which seems to have escaped most peoples' ability to understand scripture is the fact that Jewish theologians and religious thinkers used a form of referencing that could be called "abbreviated referencing", wherein they quote a verse or two of scripture, and it is to be understood by their hearers that they are referring to the whole section of scripture of which they have only quoted a verse or two. Jesus did this exact thing while on the cross, when he cried out "My God, My God, Why hast Thou forsaken Me?" That is the opening verse to Psalm 22. Jesus was not crying out in anguish over being "abandoned" by God as some have tried to say, He was calling attenion to the fact that scripture was being fulfilled right in front of those who witnessed His crucifixion. That whole Psalm is prophecy of Jesus' death on the cross, and what would happen during the time He was on the cross. Paul made use of this method too. He quoted a lot of OT scripture in his letters. When you understand what he was referring to when he did so, you will have a better understanding of Paul's doctrines, and how he arrived at them.
We do this even in modern day life. We call someone a "Judas", or a "Benedict Arnold". We sometimes quote only half of an old saying, knowing that it is understood that we mean the whole saying. "A bird in the hand..." "a stitch in time..." "What goes around...." I'll bet you can finish each one of those. I employed "abreviated referencing" and you understood what I meant, whereas if you didn't, you'd wonder what I meant by what I said, and might come up with all kinds of nutty interpretations.
In the passage in question, Paul is using an analogy to reinforce what he is saying. It is known (or should be) that all who are in Adam die, because we all know the story of Adam's fall and sin, and it's judgment and curse which fell upon all mankind. Paul contrasts that with the idea that in Christ, all are made alive. His point is, that we are in Christ the same way we were formerly in Adam. It's an important concept to grasp, because it explains how God sees us, and how we stand before Him. Paul used a parallelism to illustrate a truth, the same as Jesus did in His parables.