What Bible verses support Monasticism?

The Orthodox Exception to Monastic Celibacy

A key verse not mentioned so far is this:

30 At the resurrection they neither marry nor are given in marriage but are like the angels in heaven. (Mt. 22:30)

While this refers to the resurrection, it also provides an important guideline for monastic life, which is supposed to be an earthly manifestation of life in God's kingdom. Therefore monks may not marry. However, it is important to be aware that Orthodox tradition allows already-married men to become non-celibate monks. It does forbid single monks from marrying, however. Thus, we can add another Bible verse to the list of those already mentioned:

What God hath joined together, let no man put asunder. (Mt. 18:6)

This is a good article discussing biblical monasticism. It is written by an Orthodox Christian. Specifically, Elijah and John the Baptist are pointed to as figures of austerity and living a life outside of the world (Elijah lived as a hermit for many years). It also is aimed at rebutting Martin Luther's claim that monasticism can only lead to pride, since the works of the monk are no greater than the works of the farmer. This can also be rebutted (though the article does not mention it) by examining 1 Cor 3:10-15

10 According to the grace of God given to me, like a skilled master builder I laid a foundation, and someone else is building on it. Each builder must choose with care how to build on it. 11 For no one can lay any foundation other than the one that has been laid; that foundation is Jesus Christ. 12 Now if anyone builds on the foundation with gold, silver, precious stones, wood, hay, straw— 13 the work of each builder will become visible, for the Day will disclose it, because it will be revealed with fire, and the fire will test what sort of work each has done. 14 If what has been built on the foundation survives, the builder will receive a reward. 15 If the work is burned up, the builder will suffer loss; the builder will be saved, but only as through fire. [NRSVCE]

So we see that for Paul, some works are greater than others. Why wouldn't the life of prayer and religious vows made before God be greater than the life of the farmer? And farmers, if they so choose, can also live spiritually, even making promises to secular orders like the Benedictine Oblates. And to live according to these prescriptions of daily prayer, of offering one's work to God rather than working just for oneself or one's family, is obviously more precious in God's sight.

In addition, I have attended talks by a Melkite Catholic priest, Father Sebastian Carnazzo, in which he pointed to Paul's advice to widows as the earliest evidence of women's religious orders. 1 Tim 5:9-16 says

9 Let a widow be put on the list if she is not less than sixty years old and has been married only once;[c] 10 she must be well attested for her good works, as one who has brought up children, shown hospitality, washed the saints’ feet, helped the afflicted, and devoted herself to doing good in every way. 11 But refuse to put younger widows on the list; for when their sensual desires alienate them from Christ, they want to marry, 12 and so they incur condemnation for having violated their first pledge. 13 Besides that, they learn to be idle, gadding about from house to house; and they are not merely idle, but also gossips and busybodies, saying what they should not say. 14 So I would have younger widows marry, bear children, and manage their households, so as to give the adversary no occasion to revile us. 15 For some have already turned away to follow Satan. 16 If any believing woman[d] has relatives who are really widows, let her assist them; let the church not be burdened, so that it can assist those who are real widows. [ibid.]

Father Carnazzo contends that, in this passage, Paul is exhorting young widows not to "enter the convent" because they have a vocation to marriage. So, they should not make their pledge [to live celibately, as a sort of proto-nun] because they are not called to that life [they are called to marriage, having been married]. An important note here is that he does not speak of young women generally, but of young widows specifically, women who have shown they have a vocation to marriage. He addresses this in a free lecture series available at the Institute for Catholic Culture regarding the New Testament.

Like certain other doctrines, there is nothing in scripture that explicitly calls out monasticism as a valid way of life for Christians, but when one learns to read between the lines and put scripture in historical context, it is there in both the New and Old Testaments.