Buddhism is not a religion and I am not atheist. I am a devout agnostic
These daily precepts were created by conflating and adapting the ten precepts and the eight observances in the Uposatha Observance (AN 8:41), particularly drawing on the wording of the Uposatha Observance as transalted by Bhikkhu Bodhi in the book In the Buddha's Words. The fourth precept is also stated as refraining from incorrect speech, which is more properly aligned with the third factor of the Eightfold Path, Rigth Speech. There is a good collection of extracts from the suttas that give a broader view of this precept presented in the article Right Speech at ATI. See also Lay Buddhist Practice by Bhikkhu Khantipalo.
Thus I have heard. On one occasion the Blessed One was dwelling among the Sakyans where there was a town of the Sakyans named Nagaraka. Then the Venerable Ananda approached the Blessed One, paid homage to him, sat down to one side, and said:
"Venerable sir, this is half of the spiritual life, that is, good friendship, good companionship, good comradeship."
"Not so, Ananda! Not so, Ananda! This is the entire spiritual life, Ananda, that is, good friendship, good companionship, good comradeship. When a monk has a good friend, a good companion, a good comrade, it is to be expected that he will develop and cultivate the Noble Eightfold Path.
"And how, Ananda, does a monk with a good friend, a good companion, a good comrade, develop and cultivate the Noble Eightfold Path? Here, Ananda, a monk develops right view, which is based upon seclusion, dispassion, and cessation, maturing in release. He develops right intention ... right speech ... right action ... right livelihood ... right effort ... right mindfulness ... right concentration, which is based upon seclusion, dispassion, and cessation, maturing in release. It is in this way, Ananda, that a monk with a good friend, a good companion, a good comrade, develops and cultivates the Noble Eightfold Path.
"By the following method too, Ananda, it may be understood how the entire spiritual life is good friendship, good companionship, good comradeship: by relying on me as a good friend, Ananda, beings subject to birth are freed from birth; beings subject to aging are freed from aging; beings subject to death are freed from death; beings subject to sorrow, lamentation, pain, dejection, and despair are freed from sorrow, lamentation, pain, dejection, and despair. By this method, Ananda, it may be understood how the entire spiritual life is good friendship, good comradeship, good companionship."
Excerpted from In the Buddha's Words", Bhikku Bodhi, pp 240-241