Matthew 19:11 But he said to them, "Not all men can receive this saying, but only those to whom it is given. 12 For there are eunuchs who have been so from birth, and there are eunuchs who have been made eunuchs by men, and there are eunuchs who have made themselves eunuchs for the sake of the kingdom of heaven. He who is able to receive this, let him receive it."
First Corinthians 7:32 I should like you to be free of anxieties. An unmarried man is anxious about the things of the Lord, how he may please the Lord. 33 But a married man is anxious about the things of the world, how he may please his wife, 34 and he is divided. An unmarried woman or a virgin is anxious about the things of the Lord, so that she may be holy in both body and spirit. A married woman, on the other hand, is anxious about the things of the world, how she may please her husband. 35 I am telling you this for your own benefit, not to impose a restraint upon you, but for the sake of propriety and adherence to the Lord without distraction.
—Consecrated celibacy is an ecclesiastical practice (which can be changed), not a doctrine (which cannot be changed).
First Timothy 5:3 Honor widows who are real widows. ... 5 She who is a real widow, and is left all alone, has set her hope on God and continues in supplications and prayers night and day; 6 whereas she who is self-indulgent is dead even while she lives. 7 Command this, so that they may be without reproach. ... 9 Let a widow be enrolled if she is not less than sixty years of age, having been the wife of one husband; 10 and she must be well attested for her good deeds, as one who has brought up children, shown hospitality, washed the feet of the saints, relieved the afflicted, and devoted herself to doing good in every way. 11 But refuse to enroll younger widows; for when they grow wanton against Christ they desire to marry, 12 and so they incur condemnation for having violated their first pledge.
—The order of widows: the start of women's consecrated religious life (the first nuns). As Saint Paul states, it was the duty of these women to pray continuously, perform works of charity, and live ascetical lives with set regulations. The order was formalized by a roll; and they took vows of chastity. The earliest Christian historical writings also mention the order of widows, which eventually expanded to include consecrated virgins. Writing to the Church in Smyrna around 107 A.D., for example, Saint Ignatius of Antioch greets "the virgins who are enrolled with the widows" (Letter to the Smyrnaeans 13).