Universal mantra of all mantras for attaining the highest level of God realization?

There are a lot of mantras in our scriptures. Some of these mantras are used to invoke a particular deity, activity or a life-event. Some are mantras for longevity, some for knowledge, immortality, liberation and so on. Some of the highly notable mantras are Three Refuges, Om Mani Padme Hum, and Namo Tassa Bhagavato Arahato. **Three Refuges** > बुद्धं सरणं गच्छामि | धम्मं सरणं गच्छामि | सङ्घं सरणं गच्छामि > > Buddhaṃ Saraṇaṃ Gacchāmi | Dhammaṃ Saraṇaṃ Gacchāmi | Saṅghaṃ Saraṇaṃ Gacchāmi > > I take refuge in the Buddha. I take refuge in the Dharma. I take refuge in the Saṅgha. **Om Mani Padme Hum** > ॐ मणि पद्मे हूँ > > Oṃ Maṇi Padmē Hūm̐ > > Praise to the jewel in the lotus **Namo Tassa Bhagavato Arahato** > नमो तस्सा भगवतो अरहतो सम्मा सम्बुधासा > > Namō Tas'sā Bhagavatō Arahatō Sam'mā Sambudhāsā > > Homage to the blessed One, the Perfected One, the Fully Awakened One However, is there **one universal Mantra / Mahamantra** which can be chanted by a devotee, which takes him or her to the highest realm of God realization? Is it one of the above mantras?