Answer
Yes, but I would use the word conviction rather than boldness.
When we preach, we should speak with conviction because we ourselves are convinced of these truths through study, practice, and realization.
Our words should not simply be repetitions from a book. We should understand that these are eternal truths describing reality.
The spiritual soul may not be visible to the material eye, but it is the unseen reality underlying our existence.
Therefore, preach with humility, but also with deep conviction born of genuine realization. That combination is far more powerful than mere boldness.
