Is it realistic to hold Christians to a higher standard? To expect them to be different from unbelievers? The answer is yes. Because if there is no difference, then Christ died for nothing.
We expect more of Christians because they are more.
And as a Christian, it is the power of Jesus Christ in me that changes what I can do. My capacity increases. I am capable of more. I have a purpose to bring glory to God. I am more because I have the life of Christ in me. I am in covenant with the God of creation through the shed blood of Jesus.
That is not the same as everyone else.
My perspective is different.
My destiny is different.
I am different because of Jesus.