The concept of doubt is expressed in a couple of different ways in Scripture, and they are important to distinguish between each other. There is doubt that describes someone who is wavering (διστάζω); having two sides, and doubt that is a result of justifying a way around (διακρίνω).

Wavering is when a person is unsure, or lacking confidence. It was this type of doubting that happened to Peter after he stepped out of the boat onto the sea with Christ in Matthew 14:31 that caused him to start sinking. After the resurrection of Christ, the 11 disciples were wavering, even after seeing Him, Matthew 28:17. Wavering is not a sin but does express only having a little faith. Being of little faith is often seen in relation to how God cares for us, Matthew 6:30.

The term for doubt that could cause a Christian to sin because they are doing something while doubting is a word that means to thoroughly judge or discern (διακρίνω). “Discerning” is the positive aspect of this word where “doubt” is the negative meaning. When Abraham believed God, he did not doubt in unbelief what God was saying; rather, he took Him at His Word, Romans 4:18. He did not attempt to justify his way around what God said. If a Christian does something while doubting, they can sin, Romans 14:23. However, this is not the same as wavering or being unsure. Thoroughly judging (doubting) is being used to justify one’s actions rather than taking God at His word. In the case of food, it would be coming up with a reason to be permitted to eat something that otherwise would defile your conscience before God, such as on a special occasion, or with a specific person, rather than accepting the fact that we are now permitted to eat anything so long as it is received with thanksgiving, 1 Timothy 4:4. In Matthew 16:3 Jesus rebukes the Pharisees and Sadducees because they can discern the sky but cannot discern the signs of the times. Although they knew that Jesus was the Messiah, they doubted because they did not want their positions of authority to be taken away.

Having been with Christ during His earthly ministry, knowing that He is God in the flesh and that the Messiah will reign over Israel, the disciples faced the crucifixion of their Lord by the hands of those most trusted among the Israelites to lead them in truth. Yet, unlike any man prior, Christ did not stay in the grave. For just as the Father stated, He raised Him from the dead three days later. After the resurrection, Christ gave the disciples absolute proof that He indeed was raised from the dead. And we know from their actions after the ascension of Christ and at the beginning of the Church that they believed this without doubt. Yet, as Christ is speaking with them, before His ascension to send the Holy Spirit, they are wavering for they did not know what was coming next, Matthew 28:17. However, because of their obedience this wavering did not last very long, for after the Holy Spirit came, they were bold and spread the word of the resurrection throughout Israel, Acts 2:36. Even calling out the leaders of Israel for what they had done, Acts 4:10.

The disciples would have known of the promises given to the Messiah, especially concerning the Father’s angels watching over Him, Psalm 91:11-12. Even Satan knew this and attempted to use it against Christ, Matthew 4:6. Therefore, when Peter wavered because he was walking upon the water of the sea, it was without justification because he was not taking God at His Word. However, just before Christ ascends to send the Holy Spirit, the information on the dispensation of grace had not yet been revealed to man; therefore, their wavering is due to a lack of knowledge, not unbelief. When it comes to a Christian wavering, it is always going to come down to a lack of understanding concerning the promises God has given to the Church, or a misapplication of the promises given to Israel. Therefore, we overcome wavering through learning God’s Word and how it applies to our lives. This produces a mindset that is perceiving things as they really are and thereby becomes stable, no longer wavering because of the promises God has given to us, and the fact that He is always true to His Word.