Does God exist in living things as well as in non-living things?

The earliest spiritual treatise in the History of mankind is Rig Veda. It conveys many spiritual ideas mainly in an esoteric sense.

Rig Veda 2.1 states that AGNI is BRAHMAN.

AGNI is also called purohitaṃ - पुरोहितं.

(पुरस् + आहित) - first came into existence.

BRAHMAN means ENERGY or chaitanya, that can only be experienced, as it is an INTANGIBLE thing.

—-

And, the very 1st Rik of Rig Veda 2.1 states that Agni or BRAHMAN exists in TREES, WATER and even in STONE.

त्वम॑ग्ने॒ द्युभि॒स्त्वमा॑शुशु॒क्षणि॒स्त्वम॒द्भ्यस्त्वमश्म॑न॒स्परि॑ ।

त्वं वने॑भ्य॒स्त्वमोष॑धीभ्य॒स्त्वं नृ॒णां नृ॑पते जायसे॒ शुचिः॑ ॥

Shri Aurobindo’s Interpretation

O Fire, thou art born with thy lights, flaming out on us in thy effulgence; thou art born from the waters and around the stone, thou art born from the forests and born from the plants of the earth. Pure art thou in thy birth, O Master of man and his race.

—

Rig Veda says in an esoteric manner that BRAHMAN resides in every being, unknown to the being.

It also says BRAHMAN remains hidden in a CAVE or in a secret place, guarded by enemies. It also says that all beings are in the BRAHMAN.

It actually indicates that we cannot experience the BRAHMAN, though resides in every being, till we overcome our weak tendencies/wrong way of understanding, ie., our enemies.

Rig Veda 5.2.6

वसां राजानं वसतिं जनानामरातयो नि दधुर्मर्त्येषु ।
ब्रह्माण्यत्रेरव तं सृजन्तु निन्दितारो निन्द्यासो भवन्तु ॥

Shri Aurobindo’s interpretation

The king of those who dwell in creatures, he in whom all creatures dwell, is hidden within mortals by hostile powers; let the soul-thoughts of the Eater of things release him, let the confiners be themselves confined.