Did Buddhism oppose Vedic religion?

Buddhism does not oppose any relations like psychiatry or psychology does not have anything to do with other organised religions. Buddhism in a way is a treatment for stress and misery like psychiatry or psychology. Applying Buddhism you realize the root cause and cure yourself of misery. Unlike psychiatry or psychology the final solution your get is stable and permanent.

Check out the link : Why did Lord Buddha reject the Vedas?

Excerpt from the above answer :

In Sutta Nipat 192, Mahatma Buddha says that:

Vidwa Cha Vedehi Samechcha Dhammam Na Uchchavacham Gachhati Bhooripanjo.

People allow sense-organs to dominate and keep shuffling between high and low positions. But the scholar who understands Vedas understands Dharma and does not waver.

Sutta Nipat 503:

Yo Vedagu Gyanarato Sateema …….

One should support a person who is master of Vedas, contemplative, intelligent, helpful if you desire to inculcate similar traits.

Sutta Nipat 1059:

Yam Brahmanam Vedagum Abhijanjya Akinchanam Kamabhave Asattam……

One gets free from worldly pains if he is able to understand a Vedic Scholar who has no wealth and free from attraction towards worldly things.

Sutta Nipat 1060:

Vidwa Cha So Vedagu Naro Idha Bhavabhave Sangam Imam Visajja…..

I state that one who understands the Vedas rejects attraction towards the world and becomes free from sins.

Sutta Nipat 846:

Na Vedagu Diththia Na Mutiya Sa Manameti Nahi Tanmayoso….

One who knows Vedas does not acquire false ego. He is not affected by hearsay and delusions.

Sutta Nipat 458:

Yadantagu Vedagu Yanjakaale Yassahuti Labhe Taras Ijjeti Broomi

I state that one who acquires Ahuti in Havan of a Vedic scholar gets success.

Sirs, the recluse Gotama holds the doctrine of the moral efficacy of action, the doctrine of the moral efficacy of deeds; he does not seek any harm for the line of brahmins.

MN 95

In the Canki Sutta, the Buddha hints that even the learned brahmans themselves are unsure whether the Vedas are true, by their own empirical validation:

"And among the brahman seers of the past, the creators of the hymns, the composers of the hymns — those ancient hymns, sung, repeated, & collected, which brahmans at present still sing, still chant, repeating what was said, repeating what was spoken — i.e., Atthaka, Vamaka, Vamadeva, Vessamitta, Yamataggi, Angirasa, Bharadvaja, Vasettha, Kassapa & Bhagu: was there even one of these who said, 'This we know; this we see; only this is true; anything else is worthless?'"

"No, Master Gotama."

"So then, Bharadvaja, it seems that there isn't among the brahmans even one brahman who says, 'This I know; this I see; only this is true; anything else is worthless.' And there hasn't been among the brahmans even one teacher or teacher's teacher back through seven generations who said, 'This I know; this I see; only this is true; anything else is worthless.' And there hasn't been among the brahman seers of the past, the creators of the hymns, the composers of the hymns... even one who said, 'This we know; this we see; only this is true; anything else is worthless.' Suppose there were a row of blind men, each holding on to the one in front of him: the first one doesn't see, the middle one doesn't see, the last one doesn't see. In the same way, the statement of the brahmans turns out to be a row of blind men, as it were: the first one doesn't see, the middle one doesn't see, the last one doesn't see. So what do you think, Bharadvaja: this being the case, doesn't the conviction of the brahmans turn out to be groundless?"

The Buddha also rejected various Vedic practices as being superstitious.

In the Sigalovada Sutta, the Buddha rejected the ritualism behind the Vedic bath prayer ceremony practised by a young householder by the name of Sigala, and put a new spin on it, according to the Buddha Dhamma.

More can be found in the Brahmana Samyutta (SN 7):

• In SN 7.8, the Buddha rejected food ritually chanted over from the Vedic fire sacrifice because he discouraged superstition. By accepting the food, he would be validating the notion that the sacrificial milk rice is special and meant for noble ones.

• In SN 7.7, the Buddha says that austerities does not make one pure and chanting mantras does not make one a brahmin.

• In SN 7.9, the Buddha challenged the superstition of caste by birth.

• In SN 7.21, the Buddha enlightened a brahmin who held the superstitious view that purification rites using water can wash away sins.

In SN 42.6, the Buddha rejected the use of prayers to help the deceased go to heavan.

In DN 2, the Buddha forbade his monks from doing fire oblations or fire sacrifices, practising astrology, reading omens, calculating auspicious dates for marriages, consecrating sites for construction and worshipping the Sun.

The Buddha disagreed with Vedic teaching in certain respects, but he wasn't opposed to everything. He rejected the idea that there was any sort of intrinsic value to people's Varna, or caste, and he rejected many of the teachings which had some Brahmins of the time had understood from the Vedas (For example, at the time of the Buddha, some Brahmins taught that the creator God Brahma was eternal and all powerful) but that doesn't mean that the Buddha opposed himself to absolutely everything related to the Vedic religion of the time.

For example, although he rejected the idea that the Vedic rituals had any bearing on obtaining enlightenment, he never said that it is somehow wrong to preform the Vedic rituals. In fact, the Buddha had lay disciples who were Brahmins, and it seems reasonable to assume that at least some of them were functioning as priests.

In other words, the Buddha opposed the aspects of Vedic religion which were bad, but didn't really have much of an issue with the more neutral matters of Vedic religion.

From my reading it appears he didn't oppose Vedic religion though he dismissed the Brahmins of his times as being false Brahmins.

In the brāhmaṇavagga of the aṅguttara nikāya 5. 20, and the Dhp. 26 the Buddha reframes what it means to be a Brahmin, to one who is pious, celibate, free of mental defilements etc. - namely all the qualities of an arhat or other members of the Ariyas.

In the AN brāhmaṇavagga he debates several Brahmins, and shows a superior understanding of Brahminical history, and teaches that the present fallen state of Brahmins was not always so. In old times, per the teachings of the ten Rishis (Aññhaka, Vàmaka, Vàmadeva, Vessàmitta, Yamtaggi, Angãrasa, Bhàradvàja, Vàseññha, Kassapa and Bhagu) the meaning of Brahmin was equal to what the Buddha teaches, but over the years it had decayed to the point of being riddled with flaws.

I don't want to quote lengthy sections of the chapter on Brahmins here, but suffice to say, he wasn't opposed to the Vedas.

In AN 5.20 he mentions mastery of the Vedas as a notable feature of a good Brahmin, but by reading other suttas in the vagga we see it not the only criteria. If anything, he emphasises pious conduct and freedom from mental defilements a lot more.