Mt 8:8 "... only speak a word, and my servant will be healed."
Faith takes God at His word. But it could also be said that faith takes God at His work. A man who has saving faith can very well say, taking it from this verse: "Only do the work and my servant will be saved."
Two thousand years ago, the Lord Jesus Christ did the work. He finished it. He died for all our sins and rose again from the dead. There's the work all done for you. And now He is proclaiming it through His messengers. He has done the work. He has been saying the word through the Gospel message: "Christ died for the sins of sinners and rose again from the dead."
Will you trust in His work and His word?
