Sin has become a collective force under the Christian worldview, where under the Jewish one it was merely missing the mark. Sin has it's own reality within Christianity.
This is a good point, but I think both viewpoints have some basis in truth. Mainstream Xianity DOES seem to identify sin with specific actions--lying, cheating, eating meat that has been offered to idols, etc.--while the Jewish interpretation is really closer to the meaning of the word ("missing the mark"). Essentially, sin IS "separation from God." It is not any particular act, but it is anything that separates us from God.
"Everything is permissible (allowable and lawful) for me; but not all things are helpful (good for me to do, expedient and profitable when considered with other things). Everything is lawful for me, but I will not become the slave of anything
or be brought under its power." --1 Corinthians 6:12 (Amplified Bible)
"All things are legitimate [permissible—and we are free to do anything we please], but not all things are helpful (expedient, profitable, and wholesome). All things are legitimate, but not all things are constructive [to character]
and edifying [to spiritual life]." --1 Corinthians 10:23 (Amplified Bible)
Now, sin may end up including some specific acts every time (like you can't really blaspheme WITHOUT separating yourself from God), but no act is defined as sin except to the extent that it separates you from God.
The bottom line is that we are all fundamentally separated from God by our human nature of selfishness, in contrast to God's nature of love. The opposite of love is not hate, it is selfishness, and when you act in selfishness, you separate yourself from God--and that's what we do as humans trying to survive, we act in self-interest instead of love all the time.
And so it is our collective separation from God--our existence in a state of sin--that made it necessary for Christ to bridge the gap back into the presence of God by taking on a human nature and trumping it (so to speak) by divine nature. (Again, don't ask me for the metaphysical mechanics of that.) In that sense, sin IS a collective force, as we are all doomed to share in the selfish human nature of Adam, as Adam was an allegory for mankind, fundamentally separated from God by a human nature opposed to divine nature, a selfish nature that wanted to be his own god.
That's an awfully compact Reader's Digest version, so if I need to flesh it out a bit, let me know--but I basically just wanted to confirm what you were saying about sin being misunderstood by Xians at times.