The wrongness of suicide, for most people, is related to the value life is thought to inherently possess. It is regarded as a blessing and a gift to even have the opportunity to be alive in the first place, so how could anyone discard something so precious? A disinterested, neutral analysis of life does not support these assumptions, in my opinion. At the very least, life carries with it some inevitable and onerous obligations. Life is a situation where no action is seemingly exempt from causing harm to others.
From a Christian perspective, it would make sense if this were acknowledged and suicide were regarded as potentially noble and self-sacrificing in the very sense preached by Jesus. To put it more concretely, if all of my future actions are bound to cause harm, and I can prevent this harm by killing myself, the spirit of Christian ethics would seemingly hold such an act of total surrender of self-interest as exceptionally Christlike.
One imagines, for example, the prisoner of conscience who has been captured by enemy forces. They plan to torture her until she gives up the location of her friends and family. If she lies, they will continue torturing her until she tells the truth. She knows that there is a certain threshold of physical pain beyond which she will no longer be able to safeguard the information about her loved ones. In an act of defiance against her captors and for the sake of the others, she commits suicide, abandoning her self-interest totally and unconditionally in favor of preventing harm, in a scenario where all other options are exhausted.
I would think that Christians would regard her act as extremely praiseworthy, as it embodies all of the qualities that Christ emphasized most: putting others first, giving up everything, yielding to the welfare of your neighbor, not putting up a fight against your enemies.
But to most Christians, and especially Catholics, the reality is otherwise. Somehow it has been accepted that any behavior that results in a person ending his or her own life is a sin of deep offense, and will result in eternal damnation. I used to struggle to understand this. But now that I grasp somewhat how religions sprung up in response to economic realities and class struggles, it makes sense. Suicide is one of the most subversive acts someone can undertake if they are being exploited. Along with the usual invocations to regard the lawmakers and landowners of society as closest to heaven, the injunction against suicide in many religions was most likely a strategy of keeping servants alive as long as possible for their masters. The spirit of Christ's teachings are not reflected by it.
