A brief explanation of Matthew 25: 1-13 Those bridesmaids belong to the Bridegroom who will come back. They represent the Christians. And Jesus is that Bridegroom. They are a lamp in Christ by the baptism in the name of Jesus. The oil in their lamp represents Gods Spirit and Gifts that they received by the laying on of hands. And the spare oil concerns the growth of the actively applied Spiritual gifts: the Fruit of the Spirit.
How you yourself become an 'oil lamp' in Jesus?
You become a Christian by following Jesus in word and faith in 1 true God and in 1 Lord Jesus (see John 17: 3 and 14:1). The confirmation of your faith in Jesus is the baptism of faith in Jesus name (only) as we know from Romans 6: 3 . That is how you actually came to Jesus, says Galatians 3:27.
Thus you have become a worthy temple (‘lamp’) to receive God's Spirit in later on (Ephesians 2:21 and Hebrews 3: 6).
How do you get oil in your lamp?
Oil here stands for God's Spirit and Spiritual Gifts, so that God truly lives in your temple house (1 Corinthians 3:16, 1 Corinthians 6:19). HE is burning or living in you; that is how you are His Temple in Christ.
After the baptism of faith through which you came to Jesus and became a pure temple, you can receive God's Spirit and Gifts through the laying on of hands with prayer requests to GOD. HE can then give you the Spirit and give the Gifts. We know this from Acts 19: 5-6 and Acts 8: 16-18 . From after the period of the outpouring of the Spirit, the Apostles teach the laying on of hands to receive Gods Spirit and Gifts and act accordingly. With the Spiritual Gifts that have been received in this way you have to go out personally and pro actively in your living environment (Matthew 25: 20-21) and in this way accretion of Talents is given after effort (= Spare oil = Fruit of the Spirit).
How do you get the spare oil?
Active deployment of the spiritual gifts received (after the laying on of hands) ensures the growth of the received gifts. On the one hand you remain alive in your faith, on the other you grow in the Fruit of the Spirit. The girls without spare oil (=without active deployment of Gifts) fall asleep and do not get eternal life. They do not see the Bridegroom again. And when they wake up, they still do not get eternal life.
Fruit of the Spirit (Galatians 5:22 and Ephesians 5: 9) :
Waiting for the Second Coming of Jesus
As a Christian you do not stand about doing nothing while waiting for the Second Coming of Jesus, but you stay active and do expect that Jesus will come back at a certain moment (John 14: 3). Namely, being sent back by God at a time that only God knows ( Mark 13:32, Matthew 24:50). So there is no instant heaven or hell, but a resurrection to life in which the angels take you to Jesus in the air above Earth to assemble everyone and to go out to God in heaven (1Thessalonians4: 14-18) where Jesus has prepared us a place to live (John 14: 2).
Meanwhile, stay an active Christian!
As we know from the story of the bridesmaids (Matthew 25:5-6) the Bridegroom came very late again; in the middle of the night when it was dark. With that example Jesus refers to the darkness of the End Times. And in that dark, the bridesmaids take spare oil with them. During that expectation of the Second Coming of Christ you as a Christian are thus proactively engaged through the use of the Spiritual gifts, with which you go out, teach, evangelize, baptize, drive out demons, heal, and so on. If a Christian has received the Gifts but does not do anything with them, he/she will die for eternity and no salvation will be possible as can be read in Hebrews 6: 4-6 and Matthew 25:30.
Remain faithful to God's Commandments
In addition to the active use of the Spiritual gifts, you must also remain faithful to God's 10 Commandments as is written in Revelation 14:12 and keep the testimony of Christ. These are all 10 Commandments of God, so also the Sabbath Commandment, so keeping the Friday sunset to Saturday sunset as rest day. (Church Sunday is not God's Sabbath!).
Also in your daily life you are and remain a Christian in faith and practicing. And if you sin against God, Commandment or your loved ones, you permanently need your daily prayer, asking forgiveness from God in Jesus name (John 16:23) or directly from Jesus (John 14: 13-14) as your Lord and High Priest in the presence of God (Hebrews 4:14).
Thus you stand as a Christian every day ready for the Second Coming of Christ and you can rely on salvation to eternal life. And so you get access to the Feast in Heaven where Jesus has prepared us a place!
Praying in a Biblical way
Forgiving someone gives life!
The End Time