In Matthew, chapter 18, verse 20, it says, “If you have faith as a grain of mustard seed, you can say to this mountain, ‘Be removed and cast into the sea, and it shall be so’.” At first glance, this verse could appear to mean that we should have the power, by faith, to ‘move mountains’ or anything else we desire. But, of course this is not in accord with the rest of scripture. So why does Jesus say this to His disciples?
The context of this verse is in regards to faith. He says to them that if they had faith, a very minute amount, (as a mustard seed) they would be able to do great things. So then, what is faith and what does He mean? First of all, I think this points out that a tiny bit of genuine faith is worth more than buckets of fake faith. Why? Because true faith is NOT a THING that we can use to DO things which we desire. The whole basis of true faith is built upon the One in whom the faith (trust, obedience, reliance upon…) is placed. This means that what true faith would bring about is what He is doing, what He desires, what He orders, and what He Himself will do. A grain of faith, if it has its source in Jesus Christ and is unto the fulfilling of God’s eternal purpose, is great enough for God to use to form Christ within. (If our old Adam nature is not a mountain, what is?)
Secondly, in regards to works which God would do through us, we don’t decide what they should be and then lay hold of them “by faith”. No, they must have their source in Him, and He must be the One who carries them out through those who are seeking to take their lives out from Him. True faith is NEVER used to get my way, but to yield to His.
This is summed up in Galatians 2:20, where Paul says, “The life I now live, I live by the faith OF the Son of God…”So, it is in the end, His faith for His purpose that will “cast mountains into the sea.”