Many people who smoke cigarettes know the dangers of smoking, yet this awareness does not cause them to stop.
This is not because they fail to understand the danger, but rather because the “picture” of the danger is not powerful enough to create a feeling of threat in their hearts that will motivate them to take action.
Similarly, when a person is able to imagine and preserve in his mind a sufficiently tangible image of God’s greatness, this will create a living and revealed feeling of fear or love.
If he cannot do so but can only reach a theoretical understanding of the divine existence, he will reveal natural love and fear in his mind only, but not in his heart.
Rabbi Adin Steinsaltz