Argument from conscience
The argument from conscience is an argument for the existence of God based on the moral superiority and intuitive knowledge of our personal conscience. It is similar to the moral argument while allowing for moral relativism.
- "The simple, intuitive point of the argument from conscience is that everyone in the world knows, deep down, that he is absolutely obligated to be and do good, and this absolute obligation could come only from God. Thus everyone knows God, however obscurely, by this moral intuition, which we usually call conscience. Conscience is the voice of God in the soul. "
In this context, conscience is not just a feeling but "the knowledge of what is right and wrong: intellect applied to morality".  The argument is alluded to in the New Testament, Romans 2:14-15 .
- Everyone has a conscience that, while potentially different from everyone, is morally authoritative for me. There is "one moral absolute for everyone: never disobey your own conscience."
- The moral authority did not come from natural drives because it does not account for the absolute, without exception authority of conscience
- The self cannot morally obligate the self. "This utterly fails to account for why it is always wrong to disobey or change the rules."
- Society has no right to morally obligate an individual
- Abstract ideas that do no have an actual existence cannot obligate an actually existing person
- There is no naturalistic explanation and the source of moral obligations must "something superior to me"
- God is the source of moral authority
Authority of the conscience
The argument claims that "we have a moral obligation to follow our conscience" or "we ought to follow our conscience". However, our conscience provides us with our moral compass and "what we ought to do". Therefore, the premise of the argument reduces to "we ought to do what we ought to do" or "it is moral to be moral", which is a tautology.  In other words:
- Conscience comprises knowledge of moral actions
- It is moral to take actions based on the conscience
- Therefore it is moral to take moral actions (which is a tautology)
For this reason, the "authority" of the conscience arises from the nature of the moral values that it contains.
Practically speaking, the argument asserts that everyone agrees to "never disobey your own conscience" but their actions show that people frequently ignore or violate their consciences.
Conscience and its alleged authority is a sensation or mental process. Outside influences such as parents or society do not need a "right" to instil their principles into people, just the means to do so. The argument requires the authority must come from an agent with the right to assert their authority. This assumes moral realism without properly supporting the idea. It is assumed that God has the right to establish morality, which is again just assumed and not properly established.
The argument makes a false distinction between instinct and conscience. We have competing impulses and desires, we label one as conscience but it has no standing among our other urges or motivations. Conscience is not always unified, particularly in new moral situations.
Alternatively, conscience arises from the sub-conscious and we confabulate a moral justification. That accounts for the negative feelings for ignoring the conscience. To account for conscience by claiming "God did it" because there is "no other explanation" but without considering the subconscious is an argument from ignorance.
- "The following proposition seems to me in a high degree probable—namely, that any animal whatever, endowed with well-marked social instincts, [...] would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become [well developed ... As] soon as the mental faculties had become highly developed, images of all past actions and motives would be incessantly passing through the brain of each individual: and that feeling of dissatisfaction, or even misery, which invariably results, as we shall hereafter see, from any unsatisfied instinct, would arise [... For] conscience looks backwards, and serves as a guide for the future."
The evolutionary origins of conscience is still an area of research and debate in modern science.  The origin of conscience can probably be explained using just naturalistic processes.
- Main Article: Existentialism
Existential morality considers the one can obligate one's self and that is the only possible source of obligation. It is only necessary to generate the feeling of obligation rather than depending on an objective (and imaginary) right to justify the authority of conscience. The fact that a self generated obligation is not an absolute obligation is irrelevant since we have already accounted for the subjective phenomena we seek to explain.
Kreeft argues that abstract concepts and ideas are not in themselves binding and do not prevent different concepts being adopted in future.  However, the specific moral code and the authority of conscience are two separate issues. In reality, people follow their conscience but modify their moral values through their life, so this is not even an objection.
Other forms of conscience
If God is the cause of obligation of conscience, there are significant omissions and inconsistencies that must be explained:
- Some people feel obligation but not absolute obligation to follow their conscience 
- Some people don't seem to have a conscience at all. When combined with a tendency for violence, these people are called psychopaths. 
- Children are born without conscience or only in a precursor form.  Sigmund Freud thought that parental authority was internalized during childhood to form the super-ego.
Unless these inconsistencies are explainable, the argument implies an imperfect God due to the incomplete presence of conscience.
Situations to disobey conscience
There are situations in our conscious reflects our earlier values but we then wish to modify our behaviour and adopt different values. In this case, our conscience may be like an anchor which is resists a change in values. Concerning adoption of new values, Friedrich Nietzsche wrote:
- "The voice of the herd will still echo in thee. And when thou sayest, "I have no longer a conscience in common with you," then will it be a plaint and a pain. Lo, that pain itself did the same conscience produce; and the last gleam of that conscience still gloweth on thine affliction. "
- Peter Kreeft, The Argument from Conscience 
- Jason, Comment on Kreeft’s Argument from Absolute Conscience Fails Absolutely, 2013 
- Charles Darwin, The Descent of Man, 1871 
- , Bob Seidensticker, Kreeft’s Argument from Absolute Conscience Fails Absolutely, October 29, 2012
- Daniel D. Moseley, Gary J. Gala, On the Nature of Psychopathy, 2013
- Grazyna Kochanska and Nazan Aksan, Children’s Conscience and Self-Regulation, J Pers. 2006 Dec; 74(6):1587-617.
- Friedrich Nietzsche, Thus Spake Zarathustra
- Kreeft’s Argument from Absolute Conscience Fails Absolutely, Bob Seidensticker, October 29, 2012
- Dr. Jeff Mirus, The Argument from Conscience, Sep 22, 2009