The first altar mentioned in the Word was the one built by Noah after he came out of the ark, after being saved from the great flood. On that altar, he sacrificed clean animals to the Lord.

Mountains represent the Lord because of their height; we need to raise our thoughts above worldly things when "talking" with the Lord. An altar is a small artificial mountain. When it's used in worship, it can call to mind this raising of thought. The fire and smoke that rise from an altar are symbolically being sent to the Lord.

Most altars were made from unhewn stones. Stones represent truths. Unhewn stones - ones that have not been shaped by men - represent truths from the Word, truths that have not been adulterated.

The clean beasts to be sacrificed represent good things, charitable acts done because they are right. The clean birds represent thoughts about doctrine and actions, and about what is right. Presenting these things is an acknowledgment that we have them from the Lord, and a giving thanks to Him for them.

In the Israelitish Tabernacle, the altar of burnt offering represented the acknowledgment of good and the altar of incense that of truth. For this reason this larger altar, which was outside by the door, was made of brass which signifies natural good, while the altar of incense was made of gold, which signifies love to the Lord from whom comes truth.

2116. That 'were circumcised by him' means that they were made righteous by the Lord becomes clear from the representation and consequently from the meaning of 'being circumcised' as being purified, dealt with above in 2039. 'Being circumcised by him' - that is, by Abraham - was also a representative act, that is to say, an act of being purified and so of being made righteous by the Lord. As regards righteousness however, the position is not as people commonly suppose. They imagine that all evils and sins are washed away and completely abolished when people become believers, even if they become such only in their last hour before they die, no matter whether they have committed evil and disgraceful actions throughout the whole course of their lives. I have been fully informed however that not even the smallest evil a person has thought and carried out during his lifetime is washed away and completely abolished, but that everything remains right down to the smallest detail.

[2] The truth of the matter is that in the case of people who have thought and practiced acts of hatred, revenge, cruelty, and adultery, and so have not led charitable lives, the life they have acquired in so doing awaits them after death. Indeed every single facet of that life awaits them and gradually reappears. This for them is the source of torment in hell. But in the case of people who have led lives of love to the Lord and of charity towards the neighbour all their evils of life await them also; but these are moderated by the goods which they have received from the Lord through the life of charity during their lifetime, and in this condition they are raised up into heaven. Indeed they are withheld from the evils which they have with them so that these do not show themselves. People in the next life who doubt that they have evils with them because they do not show themselves are brought back into those evils until they know that it really is so. After that they are raised once more into heaven.

[3] This then is what being made righteous entails, for in this way people come to acknowledge not their own righteousness but the Lord's. When people say that those are saved who have faith, they are saying something that is true; but in the Word nothing else is meant by faith than love to the Lord and charity towards the neighbour, and so a life that is derived from those loves. Matters of doctrine and established beliefs do not constitute faith yet are part of faith, for these, each and every one, exist to the end that a person may become such as they teach. This becomes quite clear from the Lord's words about all the Law and all the Prophets, that is, the doctrine of faith in its entirety., consisting in love to God and love towards the neighbour, Matthew 22:35-40; Mark 12:28-35. The fact that no other kind of faith which is truly faith can possibly, exist has been shown in Volume One, in 30-38, 379, 389, 724, 809, 896, 904, 916, 989, 1017, 1076, 1077, 1121, 1158, 1162, 1176, 1258, 1285, 1316, 1608, 1798, 1799, 1834, 1843, 1844, and that heaven itself consists in love to the Lord and in mutual love, in 537, 547, 553, 1112, 2057.