Altruism is at the heart of Christ's message, to love others as yourself, even your enemies, doesn't just earn your salvation, I think it is your salvation and the salvation of others as well.
And if altruism is salvation then it follows than selfishness is destruction. Selfishness means that everyone and everything else comes second to your wants and desires, so it is easy to see how and why it becomes such a destructive essence in society and in a person.
Altruism though becomes the greatest good in a society or in an individual because it is an all for one and one for all mentality which serves all according to need and benefits all. There is no greater accomplishment than living out the altruistic message Christ preached.
It's an accomplishment because it is so rarely lived, most people do well to live by rules but Jesus gave us only 3 and they were more geared toward living by principles than by a code of law. By living by the codes to love God, to love your neighbor and to love one another as Jesus loved us, we learn to go the extra mile in any situation. To ask ourselves what is the most loving approach to this situation is to ask what would Jesus do.
Altruism is that selfless service that soldiers live by to truly serve their countrymen and their brothers in arms, it is that sense of sacrificing wants for the needs of others as monks in every religious tradition do.
It is that sense of baptism by fire that the men and women who march with Dr.King or Gandhi had when they persevered through beatings and jail times and untold injustices that granted civil and national rights for millions of others, they sacrificed so much so that others could benefit.
Jesus was Master and Lord yet He served so many.
4 He riseth from supper, and laid aside his garments; and took a towel, and girded himself.
5 After that he poureth water into a bason, and began to wash the disciples' feet, and to wipe them with the towel wherewith he was girded.
6 Then cometh he to Simon Peter: and Peter saith unto him, Lord, dost thou wash my feet?
7 Jesus answered and said unto him, What I do thou knowest not now; but thou shalt know hereafter.
8 Peter saith unto him, Thou shalt never wash my feet. Jesus answered him, If I wash thee not, thou hast no part with me.
9 Simon Peter saith unto him, Lord, not my feet only, but also my hands and my head.
10 Jesus saith to him, He that is washed needeth not save to wash his feet, but is clean every whit: and ye are clean, but not all.
11 For he knew who should betray him; therefore said he, Ye are not all clean.
12 So after he had washed their feet, and had taken his garments, and was set down again, he said unto them, Know ye what I have done to you?
13 Ye call me Master and Lord: and ye say well; for so I am.
14 If I then, your Lord and Master, have washed your feet; ye also ought to wash one another's feet.
15 For I have given you an example, that ye should do as I have done to you.
16 Verily, verily, I say unto you, The servant is not greater than his lord; neither he that is sent greater than he that sent him.
17 If ye know these things, happy are ye if ye do them. John 13:4-17
And Jesus gives us another example of service.
32 And before him shall be gathered all nations: and he shall separate them one from another, as a shepherd divideth his sheep from the goats:
33 And he shall set the sheep on his right hand, but the goats on the left.
34 Then shall the King say unto them on his right hand, Come, ye blessed of my Father, inherit the kingdom prepared for you from the foundation of the world:
35 For I was an hungred, and ye gave me meat: I was thirsty, and ye gave me drink: I was a stranger, and ye took me in:
36 Naked, and ye clothed me: I was sick, and ye visited me: I was in prison, and ye came unto me.
37 Then shall the righteous answer him, saying, Lord, when saw we thee an hungred, and fed thee? or thirsty, and gave thee drink?
38 When saw we thee a stranger, and took thee in? or naked, and clothed thee?
39 Or when saw we thee sick, or in prison, and came unto thee?
40 And the King shall answer and say unto them, Verily I say unto you, Inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me.
41 Then shall he say also unto them on the left hand, Depart from me, ye cursed, into everlasting fire, prepared for the devil and his angels:
42 For I was an hungred, and ye gave me no meat: I was thirsty, and ye gave me no drink:
43 I was a stranger, and ye took me not in: naked, and ye clothed me not: sick, and in prison, and ye visited me not.
44 Then shall they also answer him, saying, Lord, when saw we thee an hungred, or athirst, or a stranger, or naked, or sick, or in prison, and did not minister unto thee?
45 Then shall he answer them, saying, Verily I say unto you, Inasmuch as ye did it not to one of the least of these, ye did it not to me.
46 And these shall go away into everlasting punishment: but the righteous into life eternal. Matthew 25:32-46
This details the spirit of the principles Jesus asks us to live by. Sowing genuine compassion for even strangers is not a common trait, neither are the rest of the examples of service in this last example.
Cain. An example of one who had no concern for others (Genesis 4). Most are familiar with the story of Cain -- how God rejected his sacrifice while accepting that of Abel, his brother. Cain, jealous of his brother and having no regard for anyone but self, murdered his brother. When God afterward asks him where Abel was, Cain responds with the question, "Am I my brother's keeper?" (Gen. 4:9). All of us must realize we are our "brother's keepers." We are to look out for the interests of others (Phil. 2:4) and to esteem others better than self (Phil. 2:3). We must love one another (1 John 4:7). Cain's selfishness caused him to hate his brother and kill him (1 John 3:11-12).
Ahab. An example of one whose selfishness led him to be concerned about things before he was concerned about people. King Ahab coveted Naboth's vineyard and pouted when he could not get it (1 Kings 21). His wicked wife Jezebel killed Naboth and then gave his vineyard to her husband as a gift. He was ecstatic. He gave no thought to Naboth or his family. He had what he wanted. Too many people place undue emphasis on things of this world and too little on people. Jesus said one cannot serve God and things (Matt. 6:24).
David. An example of a selfish attitude which caused him to seek fulfillment of his own pleasures with no regard to the cost in getting them. His selfish pursuit of pleasure caused him to sin with Bathsheba. His selfishness then led to lies and murder (2 Samuel 11). God did not allow his sin to go unpunished. He sent the prophet Nathan to expose the sin of David and to announce God's judgment upon him. Like David, far too many people today are selfishly pursuing pleasure with no regard for either consequences or the impact of their actions upon others.
James and John. Examples of those who selfishly desire power and prestige for themselves. They asked for the most prestigious and powerful positions in Jesus' kingdom (Matt. 20), not to help others, but to have their own egos inflated and fulfilled. The rest of the apostles were greatly distressed at their actions but it seems that James and John had given little thought to what the others thought or how they were affected. They wanted what they wanted and were willing to alienate themselves from their brethren in order to get it. Jesus told them their selfishness reflected the selfish attitude of the worldly-minded. Such ambitious drive today still is opposed to the teachings of Jesus. He said that those who would be great in His kingdom would be a servant of all (Matt. 20:26-27).
The Older Brother of the Prodigal (Luke 15). An example of one who had no compassion or love for others. Jesus stated to His disciples, "A new commandment I give to you, that you love one another; as I have loved you, that you also love one another" (John 13:34). While the older brother seemed to love his father, his lack of love for his brother showed otherwise. The Christian may claim to love God but if, out of selfishness, he does not love his brother, he, in reality, does not love God (1 John 4:20-21).
Many people have the attitude of the older brother of the prodigal son. He had no compassion, no joy at finding his brother alive, he thought only of the jealousy that he was not as treasured as his brother long thought dead. Many feel Jesus was wrong in pointing out that there is as much joy in heaven when a sinner repents and finds the righteous path again as this father when he finds his son who he thought was dead was actually alive. This is a hardened heart that needs to be softened.
We have good examples of what to do and what not to do, we only need to do them and to soften our hearts enough to delight in selfless service.
In early Christian communities there were so many new converts that there was often not enough food. So what was done to deal with this? All would fast until there was enough for all to eat!
Therein lies the living of the principle of love and compassion.