How really to be True Buddhist through Observance?

Unduwap Poya is this Full-moon day of December, which celebrates these 2 events:
1: The arrival of Venerable Arahant elder Nun Theri Sanghamitta, sister of Arahat Mahinda,
from India in the 3rd century B.C. who established the Order of Buddhist Nuns (Bhikkhunis).
2: The arrival at Anuradhapura of a sapling of the sacred Bodhi-tree at Buddhagaya,
brought to Sri Lanka by the Venerable Arahant Theri Sanghamitta.

Arahant Theri Sanghamitta arrives with the Bodhi Tree Sapling.

This day is designated Sanghamitta Day. Nowadays Dasasil Matas;  the ten-precept nuns,
take an active part in making these celebrations.

Arahant Theri Sanghamitta, daughter of Emperor Asoka and sister to Mahinda.  

Details on the Arahat Nun Theri Sanghamitta and the MahaBodhi Tree:
See: https://What-Buddha-Said.net/library/DPPN/sa/sanghamitta_theri.htm
and the Tree https://What-Buddha-Said.net/library/DPPN/b/bodhirukka.htm

The over 2000 years old Bodhi Tree in Ceylon. Please notice the Lay Buddhist wear all white
clothes, which was classic at Buddha's time, and still is on Poya days today in Sri Lanka!  

Video on Uposatha Observance:
https://www.youtube.com/watch?v=cUIDQd19OmY

Audio on Uposatha Observance Praxis ..
https://soundcloud.com/bhikkhu-samahita/observance-praxis-uposatha

On such Full-Moon Uposatha Poya Observance days:
Any Lay Buddhist simply joins the Three Refuges & undertakes the Five Precepts like this:
Newly bathed, shaved, white-clothed, with clean bare feet, one kneels at a shrine with a
Buddha-statue, and bows first three times, so that feet, hands, elbows, knees and head
touch the floor. Then, with joined palms at the heart, one recites these memorized lines in
a loud, clear, calm and steady voice:

As long as this life lasts:
I hereby take refuge in the Buddha.  
I hereby take refuge in the Dhamma.
I hereby take refuge in the Sangha.
I hereby seek shelter in the Buddha for the 2nd time.
I hereby seek shelter in the Dhamma for the 2nd time.
I hereby seek shelter in the Sangha for the 2nd time.
I hereby request protection from the Buddha for the 3rd time.
I hereby request protection from the Dhamma for the 3rd time.
I hereby request protection from the Sangha for the 3rd time.
I will hereby respect these Three Jewels the rest of my life!

I accept to respect & undertake these 5 training rules: 
I hereby accept the training rule of avoiding all Killing.
I hereby accept the training rule of avoiding all Stealing.
I hereby accept the training rule of avoiding all Sexual Abuse.
I hereby accept the training rule of avoiding all Dishonesty.
I hereby accept the training rule of avoiding all use of Alcohol & Drugs.
As long as this life lasts, I am thus protected by these 5 precepts...

Taking the 3 refuges and 5 precepts audio recording:
refuge_and_precepts.mp3

Then, one keeps and protects these sacred vows better than one's own eyes and children!,
since they protect you and all other beings much better than any army! They are the highest
offer one can give in and to this world! So it goes towards Nibbāna: the Deathless Element!
This is the Noble Way to Peace, to Freedom, to Ease, to Happiness, initiated by Morality,
developed further by Dhamma-Study and fulfilled by training of Meditation...

Today indeed is Pooya or Uposatha / observance day, where any lay Buddhist normally keeps
even the Eight Precepts from sunrise until the next dawn... If any wish a recognition by the
Bhikkhu-Sangha, they may simply forward the lines starting with "I hereby ..." signed with
name, date, town and country to me or join here.  A public list of this new quite rapidly growing
global Saddhamma-Sangha is set up here!

The Modern Community of Buddha's Disciples: Saddhamma Sangha:      
https://What-Buddha-Said.net/sangha/Saddhamma_Sangha.htm

Can quite advantageously be Joined Here:
https://What-Buddha-Said.net/sangha/Sangha_Entry.htm

May your journey hereby be light, swift and sweet. Never give up!

For Details on The Origin of Uposatha Observance Days:     
https://what-buddha-said.net/library/ati_website/html/ptf/dhamma/sila/uposatha.html

The Buddhist Poya Uposatha Observance Day Calendar is here:
https://What-Buddha-Said.net/various/Poya.Uposatha.Observance_days.htm