Hastings' Dictionary of the New Testament 
SELFISHNESS. —The self-sacrifice which Christ demands of all who would be His followers might lead one to imagine that Christianity was a religion of asceticism; that the Gnostic dualism of good and evil, matter and spirit, was the logical outcome of the teaching of Jesus; that God required the renunciation of all earthly things, and even of life, for the sake of the sacrifice itself. But it is a total misconception of the religion of Jesus to suppose that He makes asceticism an end. What we find Him teaching is not that the world is evil, but that the soul of man is good; that the soul is eternal, not of time, and therefore that in God alone, to whom it is akin, can it attain its complete satisfaction ( Matthew 6:19-21 || Luke 12:33-34). He demanded self-renunciation ( Luke 14:26-27; Luke 14:33), and at the same time He inculcated the absolute value of the self ( Matthew 16:26 || Mark 8:36-37). He sets moral self-love over against natural selfishness ( Matthew 16:25 || Mark 8:35), and He insists that the perfect, the eternal development of the human personality is to be found not in separation and independence, but in union and communion with universal life,—life as it is in God, life as God has put it into the world (cf. Matthew 5, 6, 7). To pour out oneself in love, to lose oneself for Christ’s sake, to give oneself to God and to the world of men, is ‘to find,’ ‘to save’ oneself in Him. To make the law of God, the Creator of the world and the Heavenly Father of each human soul, the fundamental law of one’s life, is to render all temporal and corruptible things innocuous. It then becomes possible to employ them, in a way of which the Stoic hardly dreamed, to the end of perfect self-development ( Matthew 6:33). ‘What is a man profited,’ Christ asks, ‘if he shall gain the whole world and lose his own soul?’ To preserve and to save his soul is thus a man’s highest profit, his one great task. But to seek to save it in the worldly sense is to lose it in the spiritual and eternal. Natural selfishness is humanity’s greatest danger—the great source of sin. It is manifest that our Lord accepts the common division of human nature into its two spheres of flesh and spirit. He has, it is true, no explicit psychology such as St. Paul elaborated; but to Him the natural and the spiritual man are as evidently in continual conflict as to St. Paul. It is the natural self that must be denied, that must be subjected, if the spiritual self is to grow. Each of these Christ calls the ‘self,’ the ‘life’; but it is the latter only—‘the soul’—that is of absolute value. The value of the former is but relative; and its good, which has a measure, must always be subordinated to that of the other, which is measureless. Even the gaining of the whole world by the natural self is worthless if it entails spiritual loss; for to lose the true self is to have but the life of time, is to miss that of eternity (cf. the parable of the Rich Fool, Luke 12:16-21, and the profound statement of the same truth in Christ’s Temptation in the Wilderness, Matthew 4:1-11, Luke 4:2-13). Moral self-love, therefore, consists primarily in love to God; and whenever the good of the natural self conflicts with the dictates of that love, it must be denied as a temptation of Satan ( Matthew 16:21-23). To sink the self in the sensuous and finite, to cultivate the lower nature, to lay up abundant goods, and to imagine that the joy of one’s soul is to be found therein, is to lose one’s soul; and when death comes, the loss of all is immediately manifest ( Luke 12:16-21). It is in the light of eternity that man must view the world. It is the aim of the true self to lay up treasure in heaven, that the heart may dwell continually in the atmosphere of the eternal life.
That the denial of selfish desires is not to be regarded as an end in itself, is made clear by a whole series of parables uttered by our Lord upon the subject of labour. An idle faith, an idle self-sacrifice, did not satisfy Christ. To serve God is the soul’s great aim, and at the same time its salvation (cf. parables of the Talents, Matthew 25:14-30; the Pounds, Luke 19:11-27; the Servants Watching, Luke 12:36-48; the Ten Virgins, Matthew 25:1-13; the Labourers in the Vineyard, Matthew 20:1-15). From all these it is clear that the reward is in no sense proportionate to the work done, but to the zeal and fidelity shown; and, further, that the reward is the labour itself, and grows out of it. It is true that life eternal is the grand reward, but in that life he is already a sharer who makes God’s service his aim in this world. The complete perfection of the self comes only when sin has passed away with mortal life; but there will be no gap between this world and the next. To serve God hereafter will be the heavenly joy of the redeemed, just as it is their chief joy on earth. Heaven is not idleness, but holy service rendered in perfect freedom from the constraints of sin. It is thus manifest that there is not the slightest ground for bringing against Christianity the charge of inculcating a higher form of selfishness; for selfishness implies an opposition between the self and the not-self—that the well-being of the former is sought at the cost of the latter, whereas in the religion of Jesus there is no such opposition. The good of the self is itself the good of the world, the fulfilment of the will of God; and even the reward is nothing other than the enlargement of the human powers so that the man becomes capable of yet greater labour for the world’s welfare. Selfishness is hurtful alike to self and to mankind. Spiritual self-love is the self’s completion, God’s glory and the world’s joy. By faithfulness in the unrighteous mammon, in that which is another’s, we receive that which is our own ( Luke 16:10-12).
Literature.—The Comm. on the NT; standard works on the Parables; Beyschlag’s and Weiss’ NT Theology ; Müller, Christian Doct. of Sin , i. 94–182; Martensen, Christian Ethics , ii. 282 ff.; Newman Smyth, Christian Ethics , p. 327 ff.; Laidlaw, Bib. Doct. of Man , ch. vi.; Hasting's Dictionary of the Bible, artt. ‘Flesh,’ ‘Psychology’; F. W. Robertson, Serm . 4th ser. p. 42; J. Ker, Serm . 1st ser. p. 98; R. C. Trench, Serm. New and Old , p. 112; J. W. Rowntree, Palestine Notes (1906), p. 144.
W. J. S. Miller.
Webster's Dictionary 
(n.) The quality or state of being selfish; exclusive regard to one's own interest or happiness; that supreme self-love or self-preference which leads a person to direct his purposes to the advancement of his own interest, power, or happiness, without regarding those of others.
Charles Buck Theological Dictionary 
Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
an inordinate self love, prompting one, for the sake of personal gratification or advantage, to disregard the rights or feelings of other men. It is a negative quality — that is, it consists in not considering what is due to one's neighbors through a deficiency of justice or benevolence. Selfishness is contrary to the Scriptures, which command us to have respect for the rights and feelings of others, and forbids us to encroach thereupon.