The lust of the flesh, the lust of the eye, and the pride of life are the ________ of worldliness.

The appropriate completion of the phrase is that the lust of the flesh, the lust of the eye, and the pride of life are the signs of worldliness. This terminology draws from biblical scripture, specifically 1 John 2:16, which outlines these three elements as indicative of worldly desires that can distract believers from their spiritual focus.

Using the word "signs" is fitting because it suggests that these attributes are visible indicators of a person's alignment with worldly values rather than spiritual principles. They act as markers that can help individuals evaluate their own attitudes and behaviors in relation to their faith and relationship with God. Worldliness is characterized by a focus on self-gratification and materialism, which are encapsulated in these three aspects.

In contrast, the alternatives may not accurately capture the essence of what is being conveyed. Characteristics could imply a broader range of traits, while principles might suggest foundational truths that guide behavior rather than specific indicators of worldly influence. Operating techniques could imply strategic actions rather than underlying motivations or influences. Only the term "signs" effectively captures the idea that these aspects reveal the presence of worldliness in someone’s life.