A person who spent a lot of time and effort to express gratitude to soldiers was challenged, "But ultimately it is G-d who protects us. Why are you so grateful to these individuals?"
"If someone goes out of his way to help you financially when you need it, are you grateful?" he asked that person.
"Of course I am," was the reply.
"But isn't G-d the ultimate source of the money you get?" he asked.
"Yes. But I still have an obligation to be grateful to the people who are kind to me."
"The same applies to the soldiers whose willingness to risk their lives enables you to feel more secure. Moreover, those who express gratitude to soldiers, actually increase their gratitude to G-d for His protection. Those who aren't grateful to the human beings they see, are more likely to take the Almighty's protection for granted. Instead of decreasing gratitude to Hashem, expressing gratitude to soldiers increases feelings of gratitude to the Creator of it all."
(From Rabbi Zelig Pliskin's book: Thank You! Gratitude: Formulas, Stories, and Insights: Artscroll Publishers)