The Buddha always held that he was a simple man, one among us, not a God. In fact, Buddhism is principally an agnostic philosophy. Then why does Mahayana Buddhism practice the worship of the Buddha?
For what it's worth I found the quote you referenced:
There is a message in the suttas, that it's possible to attain Awakening by following the Dharma and the Discipline which the Buddha taught.
Also a message that the Buddha is great in many ways (e.g. disciplined, generous, insightful) to have discovered and to have taught as he did.
To say "no Gods" may be an exaggeration but OK, they're relatively unimportant (and I think it's true to say that Siddhārtha Gautama was human).
And I think this quote from Vivekananda should be understood as being a bit of a paraphrase of the entire doctrine (not only of the Maha-parinibbana Sutta), e.g. "believe not because an old book is produced" sounds like a paraphrase of another/different famous sutta, the Kalama Sutta.
It's not quite right to say (may give the wrong impression to say) that the Buddha is "nothing but one of you".
In MN 26 for example he is praised by devas on his awakening; and when people try to disparage him, he contradicts them:
Traveling stage by stage, I arrived at Benares, and went to see the group of five mendicants in the deer park at Isipatana. The group of five mendicants saw me coming off in the distance and stopped each other, saying:
‘Here comes the ascetic Gotama. He’s so indulgent; he strayed from the struggle and returned to indulgence. We shouldn’t bow to him or rise for him or receive his bowl and robe. But we can set out a seat; he can sit if he likes.’
Yet as I drew closer, the group of five mendicants were unable to stop themselves as they had agreed. Some came out to greet me and receive my bowl and robe, some spread out a seat, while others set out water for washing my feet. But they still addressed me by name and as ‘reverend’.
So I said to them:
‘Mendicants, don’t address me by name and as ‘reverend’. The Realized One is perfected, a fully awakened Buddha. Listen, mendicants: I have achieved the Deathless! I shall instruct you, I will teach you the Dhamma. By practicing as instructed you will soon realize the supreme end of the spiritual path in this very life. You will live having achieved with your own insight the goal for which people from good families rightly go forth from the lay life to homelessness.’
Practices which appear to be worship -- e.g. Tradition and purpose of prostration practice -- may have various purposes that aren't quite like worshipping a God, for example:
- Expressing gratitude and rememberance
- Expression pride (i.e. comparing yourself to the Buddha) and absence of pride (when comparing yourself to the Buddha)
Speaking of prostration, Wikipedia says,
Among Buddhists prostration is believed to be beneficial for practitioners for several reasons, including:
- an experience of giving or veneration
- an act to purify defilements, especially conceit
- a preparatory act for meditation
- an act that accumulates merit (see karma)
No, the Buddhas are not Gods and Mahayana does not conceive of them as such. In fact, all forms of Buddhism - not just Mahayana - largely agree with the following:
However, let's be clear on the many ways in which Buddhism does not conceive of the Buddha:
- The Buddha did not create the universe.
- The Buddha did not create man.
- The Buddha is not singular in the sense that many are described as Buddhas.
- The Buddha was once an imperfect sentient being just like us.
- The Buddha does not pass judgement and enact cosmic justice.
- The Buddha does not cause the workings of karma.
Now, let's examine some of the ways Buddhism does conceive of Buddhas that seem to have some similarities with different definitions of "God":
- Buddhas are perfected beings.
- Buddhas have some forms of omniscience.
- Buddhas have what appears to be some forms of supernatural powers.
- Buddhas are the greatest of teachers.
- Buddhas are worthy objects of refuge.
I think most if not all extant traditions of Buddhism would agree with the above and not just Mahayana.
Now, are Buddhas worthy of "worship?" Well, I don't know about that word, but I would say they are worthy of the highest respect and veneration. They have perfected themselves for the sole benefit of others. They have perfected all virtuous qualities. If you define "worship" as the highest respect and veneration, then I would say they are worthy.
Any Buddhist of any school of Buddhism, would not consider the Buddha to be God, if they understood his teachings correctly.
In Buddhism, there is no eternal self or eternal God. In Mahayana Buddhism, there is the concept of "Eternal Buddha" based on the concept of the Buddha's Dharmakaya or Dharma Body. This is derived from the Buddha's statement to Vakkali in Vakkali Sutta:
Vakkali: "For a long time, Lord, I have wanted to come and set eyes on the Blessed One, but I had not the strength in this body to come and see the Blessed One."
Buddha: "Enough, Vakkali! What is there to see in this vile body? He who sees Dhamma, Vakkali, sees me; he who sees me sees Dhamma. Truly seeing Dhamma, one sees me; seeing me one sees Dhamma."
Dhamma or Dharma in this context, refers to the Buddha's teachings.
Vakkali wanted to see the Buddha's physical form. Why? It's because he thought there is something important and great about the Buddha. The Buddha told him basically that when you truly understood his teachings, you would know what is important and great about him. There is nothing important and great about his physical form.
So, the Eternal Buddha in Mahayana Buddhism, is basically the Buddha's Dharma Body i.e. the Buddha's teachings.
While the Buddha never talked about statues of himself, he did say that a stupa or a burial mound or memorial can be created for the Buddha in the Mahaparinibbana Sutta (which is the closest reference that I can find):
And even, Ananda, as with the body of a universal monarch, so should it be done with the body of the Tathagata; and at a crossroads also a stupa should be raised for the Tathagata. And whosoever shall bring to that place garlands or incense or sandalpaste, or pay reverence, and whose mind becomes calm there — it will be to his well being and happiness for a long time. ...
"And why, Ananda, is a Tathagata, an Arahant, a Fully Enlightened One worthy of a stupa? Because, Ananda, at the thought: 'This is the stupa of that Blessed One, Arahant, Fully Enlightened One!' the hearts of many people will be calmed and made happy; and so calmed and with their minds established in faith therein, at the breaking up of the body, after death, they will be reborn in a realm of heavenly happiness.
So, based on that, I can surmise that the function of a Buddha statue is the same as the function of a Buddha stupa, which is simply to be an inspiration to Buddhists.
This is the same reason why people in India have statues of Mahatma Gandhi, people in South Africa have statues of Nelson Mandela and people in the USA have statues of Martin Luther King or Abraham Lincoln.