¿Why do you fear, men of little faith?

Faith is and has been the key to reaching the heart of God and pleasing him because without faith it is impossible to please God. When we pray in supplication to God it is necessary that it be accompanied by faith and not doubt in order to access a positive response.
We read in the book of Matthew:

Matthew 8: 23-26
23 Then he got into the boat and his disciples followed him.
24 Suddenly, a storm rose so hard that the waves flooded the boat. But Jesus was asleep.
25 The disciples went to wake him up. "Lord," they shouted, "save us, we're going to drown!"
26 "Men of little faith," he replied, "why are you so afraid?"
Then he got up and rebuked the winds and the waves, and everything was completely calm.
New International Version (NIV).

Source
Jesus has promised to be with us at all times in the stillness as well as in the storm, all we need is to believe in order to see his glory in us.

We must never allow doubt to cast our faith on the ground since that would ruin the blessings God has for us. We can read it in these verses where the disciples faltered in the midst of the storm, doubting the omnipresence of God, for they believed that because of Jesus being asleep they would perish but he reproached him for his disbelief by telling them that they lacked faith so they were afraid.

In addition, the tranquility of Jesus in this event shows us that we must also be in any situation with stillness in our soul and peace in our hearts because our lives are in the hands of God therefore we must not be afraid because true love casts out the fear.

1 John 4:18
18 In love there is no fear, but perfect love casts out fear; because fear carries punishment. Where he who fears has not been perfected in love.
(Reina-Valera 1960)

We must believe in God without fear since he takes care of us and will give us his hand in adversity as well as in calm.
Fear does not come from God. He has given us a spirit of self-control in order to overcome every spirit of doubt and disbelief.