"'Why is my pain unceasing, my wound incurable, refusing to be healed? Will you be to me like a deceitful brook, like waters that fail?'" (Jeremiah 15:18).
Humans are complicated creatures. We can experience a full range of emotions in a single moment, reacting to the same situation with a mix of anger, relief, sadness, and even excitement all at once. It's exhausting, and it makes it extremely difficult for us to understand what we're actually thinking.
Jeremiah was a prime example of that. His book is filled with dialogue between himself and God, with him alternating between praising God and cursing the day he was born. He knew the truth about God--that He is unchanging, perfect, and trustworthy--but many times his circumstances didn't reflect that, and he reacted in a painfully human way.
Though his emotions were all over the place, Jeremiah is consistent in one key area: he was always honest. He never tried to hide his pain and sorrow from God. When he was upset, he said so, often employing brutal language to get his point across. One time he felt that God was lying to him about always being there to deliver him. He didn't mince his words; he asked God plainly where He was and if He hadn't actually left him.
God's response to Jeremiah's honesty? A direct answer. When Jeremiah questioned God's presence, God spoke to him, reminding him of His promise when He had first called Jeremiah. "'They will fight against you,'" God told him, "'but they shall not prevail over you, for I am with you to save you and deliver you'" (15:20).
In short, Jeremiah was exhausted and ready to give up. He didn't see God anywhere. But God told him to keep going, promising again to deliver him.
God is not scared of our honesty. He will not smite us for expressing frustration. Rather, the more honest we are, the better we might hear from God.