John the Baptist not only heard God vocally but he also seen God come down and lite upon Christ during His baptism but, John still doubted later in his life. God is patient with doubt. As long as we are in this human form we will always doubt. The men in the boat with the storms raging doubted they would be saved while Jesus slept below deck. The man with the son plagued with demons believed Jesus would heal him but still had unbelief. The disciples during the sermon to thousands doubted they could feed the multitude, wanted to send them away. God cares about our doubts. Having doubt doesn't concern God because He knows we are unwilling to understand His ways. God proofed to the multitudes that He could feed thousands with just a few fish. God proofed to the men on the boat that He has control over the storms. God proofed to the man that He could cast out the demons from his son. God proofed to John that He was the Christ all powerful.

Three things that can help in our doubt. First, admit it. Second, doubt your own doubt. Third, believe what you know.