Doubt comes from a lack of faith and may be the results of having some type of problem or affliction in your life. Doubting is having a lack of faith that God isn't helping you during your troubles. For if you have doubt in your heart, you may feel that God is very distant and that he doesn't care or have an interest in your life. For one to trust and not doubt God, one must have faith and believe in his/her heart that God is who he says he is. It is faith in God and in the resurrection of Jesus Christ that save us from eternal death.
Mark 009:023 Jesus said unto him, If thou canst believe, all things are possible to him that believeth. 009:024 And straightway the father of the child cried out, and said with tears, Lord, I believe; help thou mine unbelief. Matthew 008:026 And he saith unto them, Why are ye fearful, O ye of little faith? Then he arose, and rebuked the winds and the sea; and there was a great calm. Romans 004:020 He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God; John 020:025 The other disciples therefore said unto him, We have seen the LORD. But he said unto them, Except I shall see in his hands the print of the nails, and put my finger into the print of the nails, and thrust my hand into his side, I will not believe. 020:027 Then saith he to Thomas, Reach hither thy finger, and behold my hands; and reach hither thy hand, and thrust it into my side: and be not faithless, but believing. Hebrews 12:2 Looking unto Jesus the author and finisher of our faith; who for the joy that was set before him endured the cross, despising the shame, and is set down at the right hand of the throne of God. Hebrews 011:001 Now faith is the substance of things hoped for, the evidence of things not seen. Hebrews 11:6 But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him. Ephesians 002:008 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: James 001:006 But let him ask in faith, nothing wavering. For he that wavereth is like a wave of the sea driven with the wind and tossed. Matthew 017:020 And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you. Romans 010:017 So then faith cometh by hearing, and hearing by the word of God.