The ancient Romans, Greeks, Persians, Indians, and Chinese all used aromatic essences for a variety of purposes, including religious rituals. Some religions continue this practice of using aromatic botanical during religious services, at temples, before household altars, and to purify and protect.

Spirituality is a universal human experience that connects us to or brings us into greater harmony with the present moment, to self, to our fellow man, to nature, or to the divine.

Essential oils can be diffused as you pray with the intent of helping you focus your thoughts and prayers. Oils like Helichrysum, Frankincense and Palo Santo are said to enhance enlightenment and a spiritual connection with the divine.

There are 188 references to oils in the Bible. Some precious oils such asfrankincense, myrrh, rosemary hyssop and spicknard were used for the anointing and healing of the sick. The three wise men brought essential oils of frankincenseand myrrh to the Christ Child.

Sacramental oils are featured in various blessings and sacraments. There are threetypes of oils in the Catholic Church: The oil of catechumens, the oil of the sick and sacred chrism. Chrism is one of the more versatile and frequently used oils. It's also essential during confirmation ceremonies.
When praying or meditating, you can personally prefer using a candle diffuser to diffuse your selected essential oil blend, but other types of diffusers or even a room mist can be used. 

Nowadays, some people use essential oils to open the mind, enhance spiritual connections, and invite inspiration. They do so by inhaling an essential oil while meditating or through direct application of essential oils to the body.