Socrates rejects this answer, explaining that a definition of piety must show what all examples of piety have in common. Socrates then proceeds to show that this definition is inadequate. He provides two important arguments. Socrates' first argument stems from the well known fact that the gods do not always agree. If we accept the two following propositions 1.
Piety is what is dear to the gods.
What is dear to some gods is not necessarily dear to others. Something may be both pious and impious at the same time. This is a logical contradiction and sufficient grounds for rejecting Euthyphro's definition of piety. Socrates' second argument consists in showing Euthyphro that in fact he does not really even accept his own definition. Socrates explains that if something is holy just just in virtue of being dear to the gods, then it would lose its holiness if it ceased to be dear to the gods.