Repent; or else I will come unto thee quickly, and will fight against them with the sword of my mouth. (Revelation 2:16)
He told them there were some things they needed to repent of! That means they needed to acknowledge the wrong they had allowed, ask for forgiveness of it, and turn away from it to never allow it again. That is what true and sincere repentance means.
In verses 14 and 15 he laid out what was wrong amongst them, and you can read more about this in my related posts of: “Doctrine of Balaam – Placing Stumbling Blocks in the Way” and “Jesus Hates the Free-Love of False Doctrines“. Ultimately what was wrong all had to do with the false doctrines that were misleading the people in the wrong way. God has always hated false teachings!
Now notice the way God has chosen to fight against people who teach false doctrines and that corrupt the truth and the true worship: he said that he will fight against them with the Word of God, “the sword of my mouth.” Remember that back in Revelation 2:12 that he emphasized this very characteristic of Christ at the beginning of his address to Pergamos church (you can read more about this in my earlier post: “Don’t Dare Modify the Word of God – the Sharp Two-edged Sword!“)
So how does he accomplish fighting against them with the sword of his mouth? By his true and faithful ministry, who like Antipas, “… they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death.” (see Rev 12:11) His people may have been tortured and burned at the stake, but they faithfully fought against the Catholic Church with the “sword” of Jesus’ word, by preaching and living it, even “unto the death.”
Note: You also see the fullfillment of this warning above (to repent or he would fight against them with the sword of his Word) in the Thyatira age where the judgement is executed in Revelation 2:23 as: “…I will kill her children with death; and all the churches shall know that I am he which searcheth the reins and hearts: and I will give unto every one of you according to your works.” The “death” he is talking about is the one that happens when a person is made accountable to God by the preaching of the Word, but they choose to not repent at the warning. Consequently their choice becomes sin to them because they are not obeying what God has shown them. Consequently, spiritually they are separated from God – being dead in their soul. We only have life through faith and obedience to God and his Word. Without that life, we are spiritually dead!