James is really only echoing, I think, what Christ teaches in the Gospels:
But woe unto you that are rich! for ye have received your consolation. Woe unto you that are full! for ye shall hunger. Woe unto
you that laugh now! for ye shall mourn and weep (Luke 6:24-25)
Think not that I am come to send peace on earth: I came not to send peace, but a sword (Matthew 10:34).
And, perhaps most importantly:
Then said Jesus unto his disciples, If any man will come after me, let him deny himself, and take up his cross, and follow me (Matthew
16:24).
Basil the Great alluded to this particular passage in James and other teachings of the New Testament in writing on how a Christian ought to behave:
The Christian ought to be so minded as becomes his heavenly calling,
[cf. Hebrews 3] and his life and conversation ought to be worthy of
the Gospel of Christ. [cf. Philemon 1:27] The Christian ought not to
be of doubtful mind, [cf. Luke 12:29] nor by anything drawn away from
the recollection of God and of His purposes and judgments. The
Christian ought in all things to become superior to the righteousness
existing under the law, and neither swear nor lie. [cf. Matthew 5:20]
He ought not to speak evil; [Titus 3:2] to do violence; [1 Timothy
2:13] to fight; [2 Timothy 2:24] to avenge himself; [Romans 12:19] to
return evil for evil; [Romans 12:17] to be angry. [Matthew 5:22] The
Christian ought to be patient, [James 5:8] whatever he have to suffer,
and to convict the wrong-doer in season, [Titus 2:15] not with the
desire of his own vindication, but of his brother’s reformation,
[Matthew 15:18] according to the commandment of the Lord. The
Christian ought not to say anything behind his brother’s back with the
object of calumniating him, for this is slander, even if what is said
is true. [cf. 2 Corinthians 12:20; 1 Peter 2:1] He ought to turn away
from the brother who speaks evil against him; [cf. 1 Peter 3:16-17;
James 4:11] he ought not to indulge in jesting, [Ephesians 5:4] he
ought not to laugh nor even to suffer laugh makers. [cf. Luke 6:21,25;
James 4:9] He must not talk idly, saying things which are of no
service to the hearers nor to such usage as is necessary and permitted
us by God [Ephesians 5:4]
Letter XXII
The lack of asceticism in modern Christianity is something that Russian (Orthodox) cleric Averky Taushev laments in his book, The Struggle for Virtue: Asceticism in a Modern Secular Society (Holy Trinity Publications, 2014):
What is "asceticism"? What is an "ascetic"? Many secular people
among the ranks of modern Christians know the words "ascetic" and
"asceticism" by hearsay, but very few have a correct understanding of
what these words mean and express. These words ordinarily bring about
a kind of superstitious horror in modern people who consider
themselves Christians but who live far from the spirit of the Church
and who are alien to the Church and the spiritual life, being wholly
given over to a secular life of distraction.
"Asceticism" in modern secular society is normally perceived as being
something extraordinarily gloomy, almost sinister, forever removed
form "normal" human life. Many understand asceticism to be a kind of
fanatical monstrosity or self-torture, akin to walking barefoot over
burning coals or to hanging oneself up by one's ribs - as is done, for
example, by Indian yogis and fakirs, to general amazement.
Such a distorted and prejudiced attitude towards the notion of
asceticism in modern society demonstrates how far modern Christians
have departed from a correct understanding of evangelical doctrine,
how far they have "grown worldly," and how alien their understanding
has becom to the authentic spiritual life to which our Saviour, the
Lord Jesus Christ, called not certain selected, exceptional persons,
but all Christians in general.
pp. ix-x