What is the difference between “lack of faith” and “unbelief”? I’m confused about this because Jesus said his disciples were unable to heal them because of their unbelief, not their lack of faith.
In Matthew 17, we have an account of a man whose son was demon possessed. He brought him to the Lord to be healed, telling the Lord that he had taken him to His disciples, but they were not able to drive the demon from him. Let’s read Matthew 17:19-20, “Then came the disciples to Jesus apart, and said, Why could not we cast him out? 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.” The Lord explains to His disciples that it was due to their ‘unbelief’ that they could not cast out the demon, but then He explains to them, “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.” We see here that the words ‘unbelief’ and ‘faith’ are closely connected.
Let’s read Matthew 17:20 from the New American Standard Bible, which makes the meaning a little clearer. That says, “And He said to them, “Because of the littleness of your faith; for truly I say to you, if you have faith the size of a mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible to you.” We see that the meaning of the words of the Lord is that the disciples had ‘littleness of faith’. They did not have enough faith to cast the demon out of the man’s son. If they only had faith the size of ‘a grain of mustard seed’, they could command mountains to be moved. How are we to understand this?
Faith, in its most literal sense, is simply taking God at His Word. If He says it, we believe it. It’s not how much faith we have, rather it is what we have faith in. The mustard seed is one of the smallest seeds, yet if we have faith in the Lord that is only the size of the mustard seed, we can move mountains. If we can trust the Lord, we realize we can do anything He tells us to do. What mountains do you have in your way? What difficulties are inhibiting your walk with Christ? With faith in Christ, you can remove those mountains as the Lord directs.
By faith, we can perform the most difficult tasks. Let’s consider Luke 17:5-6, “The apostles said to the Lord, “Increase our faith.” The Lord said, “If you had faith like a grain of mustard seed, you would tell this sycamore tree, ‘Be uprooted, and be planted in the sea,’ and it would obey you.” The Lord had just taught His disciples about forgiveness. Realizing their own weakness and inability to forgive, they asked the Lord for more faith. Here again, the Lord points out to His disciples that it’s not the amount of faith we have, but that we have faith in His Word. The Apostle Paul wrote in Philippians 4:13, “I can do all things through Christ, who strengthens me.” With our faith in Christ, we can do everything the Lord leads us to do.
So, we see in our portion in Matthew 17, that in this instance, ‘unbelief’ and ‘lack of faith’ are basically the same. That’s not always the case. If one is living in unbelief and is still in his sins when he dies, he is destined to spend eternity in the lake of fire. We have the words of the Lord Jesus in John 8:24, “I said therefore unto you, that ye shall die in your sins: for if ye believe not that I am he, ye shall die in your sins.” (171.2)