To Understand this parable we must Understand two things:
1. that oil represents the Holy Spirit.
2. that there is no oil in the 5 virgins` lamps
Jesus was talking to Jews who were banking on self-righteousness to please God.
Virginity represents purity through self-control.
A Lamp is just a tool for containing oil and providing a wick for the energy in the oil to produce Light.
The Scripture Says the 5 Foolish virgins took Lamps but no oil .
So, we should not assume there was any oil in there lamps.
The 5 Foolish virgins represent Religious people who do not Receive Christ.
Jesus told Nicodemus: "You must be Born of the Spirit to see or enter the Kingdom of Heaven ."
When we are Born Again we are Born of the Holy Spirit. We enter the Kingdom of Heaven at that point.
The door was shut in the face of the 5 Foolish virgins because they rejected Christ and therefore were never Born of the Holy Spirit.
So, Jesus was not introducing a new Doctrine regarding acceptability to God.
He was restating the requirement that we be Born Again to enter His Kingdom.
Jesus saith unto him, I am the Way , the Truth , and the Life : no man cometh unto the Father , but by me.