How do Christians apply the Parable of the Ten Virgins to their lives?

There is a difference in terminology between the 4 accounts of our Lord and the Pauline epistles concerning both salvation and his return. The so-called "4 gospels" concern Israel, the Circumcision, who must remain faithful "to the end" to be saved (Matthew 24:13). The parable of the 10 virgins teaches this to the Circumcision. Jesus Christ was a minister to the Circumcision to confirm the promises of God to the fathers (Romans 15:8.).

Regarding the present-day joint-body of Christ, a person is "sealed with the Holy Spirit of promise until the day of redemption, and thus cannot be "unsealed." We are told to simply "wait" and not to "watch." (Philippians 3:20, I Thessalonians 1:10)

Our salvation is unconditional upon belief, while that of the Circumcision is based on both faith and works (re James, written not to the joint-body of Christ, but to the 12 tribes scattered abroad (the Circumcision who believed).

Recognizing the difference between these two different groups is essential to rightly partitioning the Word of God. Not recognizing it conflates Israel with the church and muddies the pure Pauline doctrine which is solely for the church.

Some will argue that Jew and Gentile are one in the present day church, therefore, there is no difference between the two groups, but this ignores the fact that Israel has been held in abeyance until the fullness of the Gentiles comes in (Romans 11:25). Notice that during the upcoming Millennial Kingdom of Christ, Jews and Gentiles are not equal, for Israel rules the nations with a rod of iron. Only a small remnant of Jews are coming into the joint-body of Christ where there is neither Jew, nor Gentile but a new humanity in which all are equal.

How do Christians apply the Parable of the Ten Virgins to their lives?

The use of oil in Biblical Times was fundamental to their existence in several aspects. It was used in cooking, baking, light source and healing to say the least. It was not a commodity that was hard to to find. Olive oil, in the time of Jesus was readily available at all the local markets. So the arrival of the five foolish virgins (young girls) without enough oil would be looked upon, in this parable as something imprudent in the eyes of the vast majority of the Ancient Israelites.

The parable does not criticise the virgins for sleeping, since both groups do that, but for being unprepared as they brought no oil (it is unclear as to whether the foolish virgins succeed in purchasing any oil that night: most shops would not have been open. The New Testament scholar, Dan O. Via, considers the story of the bridesmaids as an example of a tragic parable with an inverted U-shaped plot. The rising action of the parable is the preparation for the coming of the bridegroom, but a crisis occurs when the bridegroom is delayed. This is the turning point (reversal or peripety) that leads to disaster.

The parable is not written in praise of virginity, and indeed Louis of Granada, in his The Sinner's Guide of 1555, writes "No one makes intercession with the Bridegroom for the five foolish virgins who, after despising the pleasures of the flesh and stifling in their hearts the fire of concupiscence, nay, after observing the great counsel of virginity, neglected the precept of humility and became inflated with pride on account of their virginity."

Spencer W. Kimball gave an LDS perspective on the difference between the wise and the foolish virgins, and why they could not share the oil: "This was not selfishness or unkindness. The kind of oil that is needed to illuminate the way and light up the darkness is not shareable. How can one share obedience to the principle of tithing; a mind at peace from righteous living; an accumulation of knowledge? How can one share faith or testimony? How can one share attitudes or chastity.... Each must obtain that kind of oil for himself. - Parable of the Ten Virgins

It is reasonable to conclude that Christians, in general, apply the Parable of the Ten Virgins in their lives to mean that we should always be ready and prepared (este parate) to see the Lord in every possible situation that we encounter in our lives. We must always be in possession of the oil (grace) necessary to enter the Kingdom of God. That is why this parable is called into comparison to the Kingdom of God.

I believe the vast majority of Christians will agree with this interpretation.

A couple years ago, I read "The epistula apostolorum" which contained some information which adds something to consider deeply -

And we said unto him: Lord, who are the wise and who are the foolish? He said unto us: Five wise and five foolish; for these are they of whom the prophet hath spoken: Sons of God are they. Hear now their names.

But we wept and were troubled for them that slumbered. He said unto us: The five wise are Faith and Love and Grace and Peace and Hope. Now they of the faithful which possess this (these) shall be guides unto them that have believed on me and on him that sent me. For I am the Lord and I am the bridegroom whom they have received, and they have entered in to the house of the bridegroom and are laid down with me in the bridal chamber rejoicing. But the five foolish, when they had slept and had awaked, came unto the door of the bridal chamber and knocked, for the doors were shut. Then did they weep and lament that no man opened unto them.

We said unto him: Lord, and their wise sisters that were within in the bridegroom's house, did they continue without opening unto them, and did they not sorrow for their sakes nor entreat the bridegroom to open unto them? He answered us, saying: They were not yet able to obtain favour for them. We said unto him: Lord, on what day shall they enter in for their sisters' sake? Then said he unto us: He that is shut out, is shut out. And we said unto him: Lord, is this word (determined?). Who then are the foolish? He said unto us: Hear their names. They are Knowledge, Understanding (Perception), Obedience, Patience, and Compassion. These are they that slumbered in them that have believed and confessed me but have not fulfilled my commandments. 44 On account of them that have slumbered, they shall remain outside the kingdom and the fold of the shepherd and his sheep. But whoso shall abide outside the sheepfold, him will the wolves devour, and he shall be (condemned?) and die in much affliction: in him shall be no rest nor endurance, and (Eth.) although he be hardly punished, and rent in pieces and devoured in long and evil torment, yet shall he not be able to obtain death quickly."

Are there any denominations that teach in a concrete and practical way "how to keep one's lamp full of oil" (verses 3-4) and "how to be known by the Lord" (verse 12)?

The parable of the Bridegroom is a major part of the Holy Week services in the Eastern Orthodox church.

On the Holy Tuesday services:

On Holy Tuesday the Church calls to remembrance two parables, which are related to the Second Coming. The one is the parable of the Ten Virgins (Matthew 25:1-3); the other the parable of the Talents (Matthew 25:14-30). These parables point to the inevitability of the Parousia [Second Coming] and deal with such subjects as spiritual vigilance, stewardship, accountability and judgment.

From these parables we learn at least two basic things. First, Judgment Day will be like the situation in which the bridesmaids (or virgins) of the parable found themselves: some ready for it, some not ready. The time one decides for God is now and not at some undefined point in the future. If "time and tide waits for no man," certainly the Parousia is no exception. The tragedy of the closed door is that individuals close it, not God. The exclusion from the marriage feast, the kingdom, is of our own making. Second, we are reminded that watchfulness and readiness do not mean a wearisome, spiritless performance of formal and empty obligations. Most certainly it does not mean inactivity and slothfulness. Watchfulness signifies inner stability, soberness, tranquility and joy. It means spiritual alertness, attentiveness and vigilance. Watchfulness is the deep personal resolve to find and do the will of God, embrace every commandment and every virtue, and guard the intellect and heart from evil thoughts and actions. Watchfulness is the intense love of God.

We sing Troparion of the Bridegroom Matins on Palm Sunday, Holy Monday, and Holy Tuesday nights^* (text, listen to a hauntingly beautiful version here):

Behold, the Bridegroom comes at midnight,

And blessed is that servant whom He shall find watching,

And again, unworthy is the servant whom He shall find heedless.

Beware, therefore, O my soul, do not be weighed down with sleep,

Lest you be given up to death, and lest you be shut out of the Kingdom.

But rouse yourself crying: Holy, Holy, Holy, art Thou, O our God,

Through the Theotokos have mercy on us.

^* During Holy Week, services are sung "in anticipation" so you do the next day's Matins the previous night and then that day's Vespers in the morning.