You have anchored your faith in a powerful truth from Isaiah. The prophet was given one of the clearest visions in all the Old Testament of the redemptive work of the Messiah. When you declare that by his stripes you were healed, you are standing directly on the prophecy that looked ahead to the suffering servant.
It is helpful to remember that the verse you are quoting comes in a larger passage where God calls us to behold his servant. The focus is not first on what we receive, but on who he is. He is the chosen one, the one God upholds, the one in whom God’s soul delights. Before the prophet even mentions the stripes or the healing, he tells us that this servant will deal prudently and will be exalted and extolled very high. It is out of that wise, deliberate, and triumphant work that healing flows.
When the prophet describes him, he makes a surprising point. He says there is no physical beauty that would attract us to him. The world often chases after outward appearances, but here is a servant who was despised and rejected. The healing you are claiming did not come through an impressive display of human power, but through a man of sorrows who carried our griefs. The very stripes he bore were laid on him in a moment when he seemed anything but victorious. Yet that was God’s wisdom, and his word does not return void. The stripes are effective precisely because God laid our iniquity on him.
So when you speak those words with authority, remember that you are resting on the sure accomplishment of the servant. The throne has never been empty. Isaiah saw the Lord high and lifted up, long before he wrote about the suffering servant. That same Lord, who upholds his chosen one, is watching over the word you are declaring. The verse about healing is not a detached promise; it is set within the story of a servant who would be numbered with transgressors. He bore sin, and in doing so, he secured the ground on which you now stand.
May you find deep comfort in knowing that the one who was wounded for your transgressions is now the risen Lord. His word will prosper in the very thing for which he sent it. Rest in what he has already accomplished, and let that truth quiet any fear as you continue trusting him.