What does it mean to have faith and do not doubt (Matthew 21:21)?

In Matthew 21:21–22, Jesus tells His disciples, “Truly, I say to you, if you have faith and do not doubt, you will not only do what has been done to the fig tree but even if you say to this mountain, ‘Be taken up and thrown into the sea,’ it will happen. And whatever you ask in prayer, you will receive, if you have faith” (ESV). We know that faith is required to please God (Hebrews 11:6), so it’s easy to see why Jesus put such a premium on faith without doubting.

The day before Jesus told His followers to have faith and do not doubt, He had cursed a fig tree that bore no fruit (Matthew 21:18–19). The disciples are surprised the next day to see the tree withered and dead. Jesus used the withered tree as a symbol of divine judgment against unfruitfulness. And He also uses the occasion to teach them about prayer and faith. Faith is about depending on God’s power.

Biblical faith is an unwavering trust in God’s character and promises. Hebrews 11:1 defines faith as “the assurance of things hoped for, the conviction of things not seen” (ESV). God is faithful and will keep His word. Having faith and not doubting means trusting God despite any situation or circumstance. It is the conviction that nothing is too difficult or complicated for God (Genesis 18:14; Jeremiah 32:17).

Doubt is the opposite of faith. We are told to ask God for wisdom, but to “ask in faith, with no doubting, for the one who doubts is like a wave of the sea that is driven and tossed by the wind. For that person must not suppose that he will receive anything from the Lord; he is a double-minded man, unstable in all his ways” (James 1:6–8, ESV). Doubt divides the heart and mind, undermining trust in God. Jesus emphasized the importance of unwavering devotion when He commanded us to have faith and do not doubt. As believers, we must resist doubt and fully commit ourselves to God’s will.

In Mark 9, the disciples are unable to drive out a demon from a boy who had been possessed. Jesus arrives and performs the miracle Himself, and in the process He speaks twice of the need for faith (verses 19 and 23). When the disciples later inquire of the Lord why they failed, Jesus mentions the need for prayer (verse 29). So, the disciples knew what God wanted done, but they wavered in their faith and did not pray effectively. They allowed doubt to taint their prayers. God is able, but He chooses to respond to faith rooted in Christ Jesus.

The reward for having faith and not doubting is answered prayer: “I tell you, everything you pray and ask for—believe that you have received it and it will be yours” (Mark 11:24, CSB). Of course, the understood principle in prayer is that what we ask for is in agreement with the will of God. Prayers outside of God’s will cannot be truly said to be asked “in faith.” Believers are always sensitive to the fact that their prayers are subject to divine discretion.

Faith requires patience, and Abraham’s life is a remarkable example. Despite his old age, Abraham believed in God’s promise of having a son (Genesis 15:6). He did not waver in his faith regarding God’s promise; instead, he grew stronger in his belief as he gave glory to God. He was fully convinced that God was able to fulfill what He had promised (Romans 4:20–21, ESV). Having faith without doubt brings glory to God.

Overcoming fear is essential for maintaining faith and avoiding doubt. Peter was miraculously walking on the waters of Galilee, but he began to sink when he focused on the storm rather than on Christ. Jesus gently rebukes him: “O you of little faith, why did you doubt?” (Matthew 14:31, ESV). By keeping our gaze fixed on Jesus, we can conquer our fears.

Faith leads to obedience. James 2:17 says, “faith by itself, if it is not accompanied by action, is dead.” Obedience serves as evidence of faith. We must place our trust in God. Free from doubt, faith empowers us to live boldly for Jesus and glorify God. In Christ, “we have boldness and access with confidence through our faith in him” (Ephesians 3:12, ESV).

Those who “have faith” trust in Christ. Those who “do not doubt” know that everything rests in God’s hands. God overcomes obstacles and brings forth fruit for His kingdom. Let’s keep our eyes on Jesus (Hebrews 12:1–2).