Why Christians cannot account for morality
There are many reasons why Christianity is immoral, amoral, disgusting, and does not pertain to morality at all. However, I want to focus specifically on accounting for the existence of morality. Two specific points : moral autonomy and basic assumptions.
1. As much as presuppositionalists rant against moral autonomy and freethought, we are all morally autonomous - at least, every single person able to read this blog and understand it. Ironically, we simply have no choice in this matter. Whatever standard of morality we follow, was chosen on the basis of one's values. When the Christian asks us to surrender our moral autonomy to follow Christian doctrines, he is asking for a contradiction. To follow Christianity itself, or to continue to follow it (in the cases of childhood brainwashing) is a choice.
Christianity, then, is inscribed within a larger moral context, of which it is but one little subset. CHRISTIANITY CANNOT BE THE "FIRST CAUSE" OF MORALITY. Insofar as the Christian must, then, borrow from our secular worldviews in order to make the decision of following his religion, he is contradicting himself, and cannot account for that decision by using Christianity. Thus Christianity cannot, and necessarily so because it is a religion and not a necessity, account for its own moral validity.
The Christian decides to surrender his will on the basis of his corrupt values of submission, sacrifice, faith and opposition to the natural - just like the atheist decides to affirm his will on the basis of his own values of rationality, honesty and support for the natural. And all these values can be rationally evaluated, putting the action of "following Christianity and sacrificing some of one's values" on an inferior moral ground to "following one's personal values fully".
Of course, the presuppositionalist attempts to deny moral autonomy because to do so automatically puts Christianity on such inferior moral ground. As for all collectivism, Christianity is counter to the individual, therefore sacrifice must be glorified in itself, beyond moral autonomy itself, in a higher realm of thought or ontology (the latter, in the case of God and so-called "divine morality").
2. Christianity cannot account for the most obvious natural-moral assumptions we hold. Assumptions such as :
* that genocide is evil.
* that we are not guilty for the crimes of our ancestors, and born evil.
* that the worth of a man is not based on his beliefs, but on his actions.
Each of these basic assumptions is contradicted by fundamental Christian beliefs. The assumption that genocide is evil, is contradicted by the Flood, the Plagues, and the Old Testament genocides are ordained by a perfectly good god. The assumption that we are not guilty of our ancestors' crimes (and by extension, that we are separate individuals with separate actions) is contradicted by original sin. And the assumption that the worth of a man is based on his actions is contradicted by the standard of faith for salvation.
In each case, to affirm the obvious natural-moral assumption is to deny the truth of Christianity. These are all direct contradictions and there is no wiggling room for the Christian. So either the Christian rejects natural morality, which is absurd, or he keeps the contradiction, which is dishonest, or he rejects Christianity, which is the most reasonable position to take.
3. There are many stages of morality. The first kind is order-based morality : the parents or teachers give orders, and we obey. This is a necessary stage in our development : pretty simple, so I don't need to explain it. The second stage is natural morality.
Where does natural morality come from ? Part of it comes from biological evolution, as our attitudes and feelings are initially set because of evolutionary goals. Another part of it comes from the common observations we make as we grow up, and our process of maturation - our recognition that other minds exist, and that those minds have their own values, and later in life as a recognition of the needs of living in society together. We got them from the loving relationship we had with our parents, and later in life from the trust and love we have for other people. We get them still from our yearning for peace and plenty in ourselves, our family, our society, our world. All of these things are natural and don't require a religion or doctrine. Teenage rebellion is also in this category, as an affirmation of one's independence and a reaction to the previous order-based morality.
Natural morality gives us the independence, love of peace, honesty and reason we need to "graduate" to the next stage, which is rational morality. This third stage is based on the recognition that human actions have causal, measurable effects that can be used to evaluate our actions. Some of these are already present at earlier stages - for example, we learn pretty quickly that we must eat, and that not eating is bad, although we may not completely understand the whole process. But to follow rational morality is to explicitly understand the causal links between our actions and their effects, through both science and our observations of life in society.
There are four basic types of values in rational morality : physical values, spiritual (mental) values, social values and political values. There are also many virtues such as purpose, honesty, rationality, benevolence, non-coercion, Trader Principle, and so on.
Are there further stages of morality ? I think so. In my opinion, a further stage would be to be able to model social institutions and even human nature itself, with the aims of using this as a springboard for higher forms of thought. But for the moment this resides more in the realm of science-fiction.