Doubt = to lack confidence in; uncertainty; unbelief
Matthew 14:25-32 (NIV)
25 Shortly before dawn Jesus went out to them, walking on the lake. 26 When the disciples saw him walking on the lake, they were terrified. “It’s a ghost,” they said, and cried out in fear.
27 But Jesus immediately said to them: “Take courage! It is I. Don’t be afraid.”
28 “Lord, if it’s you,” Peter replied, “tell me to come to you on the water.”
29 “Come,” he said.
Then Peter got down out of the boat, walked on the water and came toward Jesus. 30 But when he saw the wind, he was afraid and, beginning to sink, cried out, “Lord, save me!”
31 Immediately Jesus reached out his hand and caught him. “You of little faith,” he said, “why did you doubt?”
32 And when they climbed into the boat, the wind died down.
Matthew 21:21-22 (NIV)
21 Jesus replied, “Truly I tell you, if you have faith and do not doubt, not only can you do what was done to the fig tree, but also you can say to this mountain, ‘Go, throw yourself into the sea,’ and it will be done. 22 If you believe, you will receive whatever you ask for in prayer.”
MATTHEW 28:16-20 (NIV)
16 Then the eleven disciples went to Galilee, to the mountain where Jesus had told them to go. 17 When they saw him, they worshiped him; but some doubted. 18 Then Jesus came to them and said, “All authority in heaven and on earth has been given to me. 19 Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, 20 and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age.”
Mark 9:23-25 (NIV)
23 “‘If you can’?” said Jesus. “Everything is possible for one who believes.”
24 Immediately the boy’s father exclaimed, “I do believe; help me overcome my unbelief!”
James 1:5-7 (NIV)
5 If any of you lacks wisdom, you should ask God, who gives generously to all without finding fault, and it will be given to you. 6 But when you ask, you must believe and not doubt, because the one who doubts is like a wave of the sea, blown and tossed by the wind. 7 That person should not expect to receive anything from the Lord.