Oil -- typically olive oil -- symbolizes the good that comes from celestial love. Celestial love is love of the Lord, the highest and purest love we can have. The good of celestial love is the desire to be good springing from celestial love: Wanting to do the Lord's will because you love Him. That's not a state many reach, even in heaven, but it's a beautiful goal. This representation makes sense based on the idea that the sun -- the source of all natural light and heat, and thus all natural life -- represents the Lord, the source of all spiritual light, heat and life. Burning oil was the most pure fire available in Biblical times, thus the closest representation of the sun people could create.

216. "'Be zealous, therefore, and repent.'" This symbolically means, in order for this goal to come about from an affection for truth and an aversion to falsity.

The text here says, "Be zealous," because it said in verse 15 above, "Would that you were cold or hot," and the meaning here is for the angel to be hot; for zeal is a spiritual heat, and spiritual heat is an affection of love, here the affection of a love of truth. Moreover, someone who acts from an affection of the love of truth acts also from an aversion to falsity. Consequently this is the symbolic meaning of the command to repent.

In the Word, when zeal or jealousness is applied to the Lord, it symbolizes both love and anger - love in John 2:17, Psalms 69:9, Isaiah 37:32; 63:15, Ezekiel 39:25, Zechariah 1:14; 8:2, anger in Deuteronomy 32:16, 21, Psalms 79:5-6, Ezekiel 8:3, 5; 16:42; 23:25, Zephaniah 1:18; 3:8.

In the Lord's case, however, zeal or jealousness is not anger. It only seems as though it were in outward appearances. Inwardly it is love. It seems in outward appearances as though it were anger because the Lord appears to be angry when He admonishes a person, especially when the person is being punished by his evil, which love permits in order that his evil may be removed. The case is entirely like that of a parent. If he loves his children, he allows them to be chastised in order to remove their evils.

It is apparent from this why Jehovah declares Himself to be a jealous God (Deuteronomy 4:24; 5:9-10; 6:14-15).