There are Theravada Buddhists who don’t worship any deities but only take refuge in Buddha, Dhamma and Sanga. There are Theravada Buddhists who also spend time and money on spirits and deities. Theravada Buddhist might pray to other deities, spirits or supernatural being.

In Tibetan Buddhism anything which helps you on your path to enlightenment is considered a good spirit while anything which opposes you or holds you back on your path to enlightenment is a demon. Greed, fear, lust, etc. are demons. Your friend might be a demon to you. Your attachment to your job might be a demon. Ignorance is the king of demons.

So you see, demons are not always literal evil or harmful spirits. But there is an exorcism that we do. But this exorcism works because of having compassion on the demon.

For example, if a demon is bothering us, there is a reason. Often it is trying to collect a debt that we owe. These debts are karmic debts. We owe, but don’t want to pay, and so the spirit coming to collect the debt merely appears as a demon. If we give it what we owe it he will leave us alone and we will be free of debt. We earn karmic debts by benefitting from something a spirit has done for us or by disturbing the spirit or taking something which belongs to it. That is why we should have respect for the environment and nature where-ever we are. We shouldn’t overturn rocks and we should leave things where they are. Never take things from nature. If you do, for example if you are harvesting herbs or food, leave a little offering to the spirits as a gesture of appreciation, recognition, and respect.

Now for the more persistent and scary demons. And this applies to the personified abstract concepts, such as ignorance, fear, etc…. We give these demons what they want. We feed them our own sense of self to them out of compassion for them. If we have taken the bodhisattva vow then we have compassion on even demons and vow to take away their suffering. Having fed the demons our own sense of self, they are satisfied, they have gotten what they want, our debt is paid, and they often transform into something benevolent and become our ally and helper. And we are the more enlightened for it as well, having surrendered the sense of self to what we fear, motivated by compassion, is the surest way to overcome self-grasping.

Metta is a good thing, as Volo says. But metta is not something to be done with the emotional intellect (mano); but with citta.

Metta comes from the Sanskrit मैत्र maitra [vr. मित्र mitra (mith-ra)].
√ मिथ् mith: to unite (as friend or antagonist).
Mitra symbolizes the social contract, and is the god of alliances in Vedism.

Metta is some kind of “diplomatical” benevolence.
And if it has to be called “love”, then it has to be a love that emanate from citta (a love of reason); not from mano (a love from the “heart”).

To understand what citta is, just softly walk a mile, thinking only about your walking.

Note:
I have been mislead for a long time by SN 10.4 that uses mano to send metta. It is when I realized that there was no mano 意識 in its parallel, that I turned to the more appropriate series of SN 20. 3-4-5 with citta 心 (慈 心 mettā citta).

Sex Change in the Pāli Canon

Two passages in the Vinayapiṭaka of the Pāli canon that is claimed by the Theravāda school of Buddhism document the possibility that a change of sex is possible in this life. In keeping with the logic of the monastic rules articulated in the Vinaya collection, the Buddha’s response focuses on which rules are broken and which are not broken, following a change of sex.
Now at that time the sexual features of a woman appeared on a certain monk. They told the
Blessed One about this matter. [He said,] “Monks, I allow the same teacher, the same ordination,
the same rainy seasons together with the nuns. I allow reinstatement among the nuns for those
offenses that nuns share in common with monks. According to those offenses of monks that are
not shared in common with nuns, there is no offense.
Now at that time, the sexual features of a man appeared on a certain nun. They told the Blessed
One about this matter. [He said,] “Monks, I allow the same teacher, the same ordination, the same
rainy seasons in relation to the monks. I allow reinstatement among the monks for those
offenses that monks share in common with the nuns. According to those offences of nuns that
not shared in common with monks, there is no offense” (Vin III.35).[2]

“tena kho pana samayena aññatarassa bhikkhuno itthiliṅgaṃ pātubhūtaṃ hoti” and “tena kho pana samayena aññatarissā bhikkhuniyā purisaliṅgaṃ pātubhūtaṃ hoti,” Vinaya-piṭakaṃ, edited by H. Oldenberg (London: Pali Text Society by Luzac & Co., 1964 [1882]), vol. 3, 34-35. With the good company and consultation of Professor Rebecca Manring (Indiana University at Bloomington), the translations of the Pāli are our own.

theravāda vinaya mahāvibhaṅga pārājikakaṇḍa

Paṭha­ma­pā­rāji­ka­sikkhā­pada

Tena kho pana samayena aññatarassa bhikkhuno itthiliṅgaṃ pātubhūtaṃ hoti. Bhagavato etamatthaṃ ārocesuṃ. “Anujānāmi, bhikkhave, taññeva upajjhaṃ tameva upasampadaṃ tāniyeva vassāni bhikkhunīhi saṅgamituṃ. Yā āpattiyo bhikkhūnaṃ bhikkhunīhi sādhāraṇā tā āpattiyo bhikkhunīnaṃ santike vuṭṭhātuṃ. Yā āpattiyo bhikkhūnaṃ bhikkhunīhi asādhāraṇā tāhi āpattīhi anāpattī”ti. #14

Tena kho pana samayena aññatarissā bhikkhuniyā purisaliṅgaṃ pātubhūtaṃ hoti. Bhagavato etamatthaṃ ārocesuṃ. “Anujānāmi, bhikkhave, taññeva upajjhaṃ tameva upasampadaṃ tāniyeva vassāni bhikkhūhi saṅgamituṃ. Yā āpattiyo bhikkhunīnaṃ bhikkhūhi sādhāraṇā tā āpattiyo bhikkhūnaṃ santike vuṭṭhātuṃ. Yā āpattiyo bhikkhunīnaṃ bhikkhūhi asādhāraṇā tāhi āpattīhi anāpattī”ti. #15

theravāda collection on monastic law monks’ rules and their analysis the chapter on expulsion (_pārājika_) The first training rule non-offenses

At one time the characteristics of a woman appeared on a monk. They told the Master. He said: “Monks, I allow that very discipleship, that very ordination, those years as a monk, to be transferred to the nuns. The monks’ offenses that are in common with the nuns are to be dealt with in the presence of the nuns. For the monks’ offenses that are not in common with the nuns, there’s no offense.

At one time the characteristics of a man appeared on a nun. They told the Master. He said: “Monks, I allow that very discipleship, that very ordination, those years as a nun, to be transferred to the monks. The nuns’ offenses that are in common with the monks are to be dealt with in the presence of the monks. For the nuns’ offenses that are not in common with the monks, there’s no offense.”

Karen C. Lang (1982: 100) argues that this figurative transformation from preoccupation with sexuality to concern with spirituality seems to be rooted in the fear and disgust of women’s bodily functions. Ascetic practices, such as fasting, will prevent menstrual flow and sexual abstinence will prevent her from bearing children. Furthermore, ‘shaving off the woman’s hair and en-joining her to wear shapeless garments, identical to those worn by monks, also contribute to the impression that women were expected to transform their female nature, physically as well as mentally’ (Lang 1982: 101).
Given these facts, strictly speaking, there is no female Sangha. Femininity is not fit for spiritual growth and has to be dropped.

The Pali canon—which comprise some of the earliest recorded teachings of the Buddha—contains numerous discourses on human emotions, motivations, and reactions, including those that are latent or unconscious. One of the three principal sections of the canon, the Abidhamma (Sanskrit, Abhidharma) Pitaka, or “Collection of Special Teachings,” is often referred to as a compendium of Buddhist psychology, as it classifies the factors of mental and physical experience and how they relate to each other. The Abidhamma also offers a course of treatment in the form of instructions for ethical conduct, mind training, and the cultivation of wisdom.

Can Buddhist monks and nuns get married and have children?

The short answer is no. The Buddha was very explicit that monks and nuns on ordaining should relinquish their household ties (except for dedication to and respect for parents) and take a vow of celibacy. That’s because full-fledged devotion to following the Buddha’s path of practice leading to enlightenment is extremely hard to accomplish when the distractions, entanglements, and obligations of romantic relationships and family life are at play. Sensual attachment, especially, is one of the most intransigent obstacles to freeing the mind from craving. The Buddha saw that separating oneself from sensual relationships and external attachments was a critical step to loosening the interior attachments of the mind.

In fact, the Vinaya—the Buddha’s code of conduct for monks and nuns—includes many rules about which relationships and family ties are permitted and which are not. These restrictions were probably established in response to actual situations that arose in the early monastic community. (There are even rules about not ordaining when pregnant and not sleeping with your former spouse after being ordained—which suggests that those things happened.)

Does Buddhism support gender equality?

As recorded in the Pali canon, which comprises some of the earliest Buddhist teachings, the Buddha praised the attainments of his female disciples but refused to ordain women until his stepmother, Mahapajapati, and his attendant and cousin, Ananda, convinced him to. Still, when women were allowed to ordain, they were saddled with eight “heavy rules” (in Pali, garudhammas) that kept them subordinate to monks. Some scholars argue, however, that this account and the eight further rules are later additions.

Theravada, in fact, denounces sexuality and distrusts sensual enjoyment. Essentially, Buddhism began with a group of celibate monks called the Sangha. The Vinaya rules were intended for monks and not for the laity.

Leonard Zwilling notes, We should not expect any term with the precise connotation of homosexuality to appear in Buddhist literature. However, homosexual behavior stemming from an apparent disposition to seek sexual gratification through relations with members of one’s own sex in preference to the other did not go unnoticed. (Zwilling 1992,
203)