The thing is, Bolognese, headinhands, when faced with a group Christians who do not believe their faith demands or particularly supports capital punishment, you seem to be insinuating this stance is somehow 'unchristian', from you own understanding of the faith, as atheists. Although there are many Christians who experience their faith in the same way, regarding capital punishment, as the posters who do not support it on this thread.
From an unbelievers perspective, Christianity simply involves living life by a book and church tradition. So if the Bible includes capital punishment, if capital punishment was carried out at any time with the church's agreement, then you would say the Christian stance would to be agree with capital punishment.
Yet for believers, their faith is much more than this, it lives in them, is interactive and responsive to each individual situation in their lives - not just a book and church tradition. Engaging with what is written in the Bible does not involve dismissing it all because there is violence, it does not involve dismissing the message of love and forgiveness, which is what is particularly predominant in the NT.
What I take from what is shown throughout the Bible is God's presence right in the midst of His people's lives, whether they be kings, warriors, fishermen, beggars or prostitutes. I don't understand it all, I don't expect to, as I do not live in a particular brutal warrior like culture. Yes, it gets horribly messy but lots of people live horrific violent, messy lives, the accounts of people's experiences in the Bible reflect this. To be true to those people, the Bible needs to tell of their experiences too.