After the meeting with Euthyphro outside of the king's court and listening to the reason why Euthyphro is here, Socrates is not persuaded that Euthyphro's prosecution of his own father for killing is pious or just thing to do. He requests Euthyphro to educate him concerning what piety and sin are, so that he may decide for himself whether the thing Euthyphro is doing to his own father is really pious action. This initiates the core of the dialogue - a rigorous conversation concerning the essence of piety.
At first, Euthyphro makes an effort to clarify to Socrates what impiety and piety are by offering him the examples. He asserts that, "pious means to do the things I am doing now, to accuse the criminal, be it about killing or theft or anything else, whether the criminal is your parent or anybody else". However, Socrates says he did not ask for the enumeration of pious and impious things; he merely wished to understand what impiety and piety are.
Then, Euthyphro tries to describe impiety and piety as follows: "what is pleasing or dear to gods is pious, and what is not - is really impious". However, previously in the conversation Socrates has already confirmed that Euthyphro has faith in the Greek gods and all of the accounts concerning them - for instance, he thinks that there is constant fight among them, and that they disagree concerning numerous issues. Recollecting this, Socrates asserts that this makes Euthyphro's definition of the piety problematic. For if what is pleasing to gods is pious, and yet if they conflict and struggle concerning what is really pleasing to them, it will appear that one single act will be impious and pious (as it will be dear to certain gods and not pleasing to the others).
After Socrates's hint, Euthyphro offers the next characterization of the piety: "pious is what all gods love, and what all the gods dislike, is impious". Socrates, then, asks Euthyphro whether "pious is loved by all gods since it is pious, or is an issue pious since it is loved by all gods?". The major concept here is that there has to be the order of clarification. Either gods admit certain pious issues and love them since they are pious, otherwise gods merely love whatever issues they do, and it is due to the fact that gods like certain things as they are virtuous. So, it appears that the readers are faced with dilemma: on one hand, if we say things are pious since gods love them, then it seems what is pious depends on the impulse of gods. For what they may love appears to be as illogical as whether you love or hate ice cream. However, on the other hand, if certain things are pious separately of gods, then it looks like the role of all gods is lessened. For why would people require all gods if some issues are pious and impious separately for them? Furthermore, describing "piety" as something what all the gods like is not getting humans any closer to realizing what piety is. For it may be very well that all gods like what is pious, however, Socrates wished to understand what the piety really was, not what the result of it was (for instance, all gods like it). This forces Socrates to protest, "you described me the result of the pious, that pious has feature of being liked by all the gods, however, you have not yet answered me what pious actually is".
Again with the help of Socrates, Euthyphro makes and attempt to assert how just actions and pious acts are connected. He declares that, "the religious and pious is the aspect of just, which is concerned with care of gods, whilst that concerned with care of humans is the remaining aspect of justice". Basically, the idea is that justice covers many issues that have to do with the gods and humans. Piety, in contrast, only has to do with just issues, which concern merely gods (but not humans). So, whilst all pious issues are just, not all just issues and things are pious. Socrates focuses on what precisely Euthyphro suggests when he asserts "pious is the aspect of just, which is concerned with the care of gods." For he believes that "care of" means bettering something, as it does when somebody cares for horses or cattle. But, certainly, Socrates argues, gods are not bettered by our pious acts, as nothing people may do can enhance the gods.
Euthyphro changes his story by asserting that the sort of care he meant was the sort of care "that slaves take of the masters'. He goes on to support the opinion that piety is (as Socrates recognizes it) "a type of the trading skill among the gods and humans". Socrates confronts Euthyphro by saying that presents are, in fact, beneficial to the recipient, however, how could gods benefit from anything humans do? In reply, Euthyphro declares that people serving the gods merely please them. Then Socrates declares that Euthyphro has come to the beginning, as it appears he is back to the supposition that pious is something that is dear to gods. Socrates starts it again, claiming that he still wishes to know what the essence of piety is, and that they "must consider again from the start what piety is". Upset, Euthyphro leaves. Hence, this dialogue ends.