Simple:
* The stars seem to shine with an eternal light.
* The memory of that day will be eternal.
Figurative:
* The lovers swore eternal love for each other.
* The artist hoped to create a work of eternal beauty.
Philosophical:
* Some believe in the eternal cycle of birth and death.
* The question of life's eternal meaning is a source of endless debate.
Literary:
* The ancient ruins whispered of a civilization that had achieved eternal glory.
* He sought solace in the eternal rhythms of nature.
Religious:
* Many religions teach the concept of eternal life after death.
* The poet described the soul's journey to an eternal paradise.
Remember, "eternal" is a strong word implying something that lasts forever or is without end. Choose the context and tone that best suits your meaning.