Everyone accepts the statements of the Bhagavad Gita as the ultimate, because it is the essence of all the Vedas as is seen in the Gita Mahatmya.
sarvopanisÌ£ado gÄvo
dogdhÄ gopÄla-nandanahÌ£
pÄrtho vatsahÌ£ su-dhÄ«r bhoktÄ
dugdhamÌ gÄ«tÄmrÌ£tamÌ mahat
"This GÄ«topanisÌ£ad, Bhagavad-gÄ«tÄ, the essence of all the UpanisÌ£ads, is just like a cow, and Lord KrÌ£sÌ£nÌ£a, who is famous as a cowherd boy, is milking this cow. Arjuna is just like a calf, and learned scholars and pure devotees are to drink the nectarean milk of Bhagavad-gÄ«tÄ." (GÄ«tÄ-mÄhÄtmya 6)
ekamÌ ÅÄstramÌ devakÄ«-putra-gÄ«tam
eko devo devakī-putra eva
eko mantras tasya nÄmÄni yÄni
karmÄpy ekamÌ tasya devasya sevÄ
(GÄ«tÄ-mÄhÄtmya 7)
In this present day, people are very much eager to have one scripture, one God, one religion, and one occupation. Therefore, ekamÌ ÅÄstramÌ devakÄ«-putra-gÄ«tam: let there be one scripture only, one common scripture for the whole world — Bhagavad-gÄ«tÄ. Eko devo devakÄ«-putra eva: let there be one God for the whole world — ÅrÄ« KrÌ£sÌ£nÌ£a. Eko mantras tasya nÄmÄni: and one hymn, one mantra, one prayer — the chanting of His name: Hare KrÌ£sÌ£nÌ£a, Hare KrÌ£sÌ£nÌ£a, KrÌ£sÌ£nÌ£a KrÌ£sÌ£nÌ£a, Hare Hare/ Hare RÄma, Hare RÄma, RÄma RÄma, Hare Hare. KarmÄpy ekamÌ tasya devasya sevÄ: and let there be one work only — the service of the Supreme Personality of Godhead.
http://vedabase.net/bg/introduction/en
And in the Bhagavad Gita, the ultimate verse is the saranagati verse and thus it is of utmost important.
Bhagavad-gÄ«tÄ As It Is 18.66
sarva-dharmÄn parityajya
mÄm ekamÌ ÅaranÌ£amÌ vraja
ahamÌ tvÄmÌ sarva-pÄpebhyo
moksÌ£ayisÌ£yÄmi mÄ ÅucahÌ£
SYNONYMS
sarva-dharmÄn — all varieties of religion; parityajya — abandoning; mÄm — unto Me; ekam — only; ÅaranÌ£am — for surrender; vraja — go; aham — I; tvÄm — you; sarva — all; pÄpebhyahÌ£ — from sinful reactions; moksÌ£ayisÌ£yÄmi — will deliver; mÄ — do not; ÅucahÌ£ — worry.
TRANSLATION
Abandon all varieties of religion and just surrender unto Me. I shall deliver you from all sinful reactions. Do not fear.
PURPORT
The Lord has described various kinds of knowledge and processes of religion — knowledge of the Supreme Brahman, knowledge of the Supersoul, knowledge of the different types of orders and statuses of social life, knowledge of the renounced order of life, knowledge of nonattachment, sense and mind control, meditation, etc. He has described in so many ways different types of religion. Now, in summarizing Bhagavad-gÄ«tÄ, the Lord says that Arjuna should give up all the processes that have been explained to him; he should simply surrender to KrÌ£sÌ£nÌ£a. That surrender will save him from all kinds of sinful reactions, for the Lord personally promises to protect him.
http://vedabase.net/bg/18/66/