(Note: When I refer to 'conscience' here, I am referring to an impulse that pulls and sways our actions and influence our beliefs, something that we cannot really defend using rational arguments. It is different from conscience in the sense of having arrived at a decision through deliberation and rational thinking)
A friend who wished to remain anonymous texted me this message, "A conscience does not prevent sin... It only prevents us from enjoying one... Heard this on Radio 4... Hmm..."
My answer to this is this - In our mind there's you, the self, which makes subjective experience possible. Subjective here does not mean having an experience influenced by your own knowledge and belief. No, subjective here simply means being able to say that you see something, you are reading this, you are thinking. If the subject i.e. you doesn't exist, then you can't have a subjective experience like you feel something, you see something, you think... in other words, Sum ergo cogito.
Other than the data from the senses that the subconscious has filtered and interpreted for you, the subconcious also throws at you what we would call impulses, and one of these impulses is what we can call conscience. What this impulse does is that it MAKES us THINK a particular act is desirable or not desirable, and sometimes it is deeper in that it can associate an act as contrary to who we are or is deeply embedded in our identity, although this is not true, the self is a clean slate, there is nothing outside of it that can be associated with it or be embedded in it. So this is how conscience operates, when you do something that is against your conscience, at a milder level, you are made to think that the act you're doing is not desirable.
Lust, similarly, has the same effect in our mind. Say you are doing the 'right' thing like restraining from premarital sex with your girlfriend or boyfriend, your subconsicous mind will tell you that this is not desirable, you know you want it. Sometimes it can also work at a deeper level, it can associate a desire with the essence of your being or identity. Think Hugh Hefner, think Anthony Weiner. Not expressing this part of you makes you feel like you're restraining a part of yourself.
But these two are essentially impulses and with some imagination we can see how conscience can be as detrimental as lust. Recall how some people restrain themselves too much under the anvil of conscience, the kind of self-denial that sprang from such restraint. Why we call one impulse conscience and the other lust, is the result of our own labelling. That labelling comes from our own upbringing and the societal pressure that acts upon us. So though they are opposite forces in our mind, they are essentially similar. They are labelled differently as a result of cultural conditioning.
I think the ideal way is to be the master of these impulses, not in the sense of suppressing them, but in the sense of acknowledging their existence and deal with them with the objective of coexistence.