Jude’s letter is one of the sharpest in the New Testament. He writes about ungodly men who crept into the church, calls them clouds without water and wandering stars, and warns of judgment. Then, near the end, he says something gentle. Have mercy on those who doubt.
That distinction matters if you are the one doubting. Maybe you prayed for something for years and it never came. Maybe you read an argument online at midnight and could not answer it. And you assume that if the church knew, you would be lumped in with the scoffers.
Jude does not lump them together. The scoffers in his letter follow their own ungodly desires and cause divisions. Those who doubt are wavering, and Jude asks the faithful to treat them with mercy instead of suspicion. Just before this, he tells believers to build themselves up in their most holy faith, to pray in the Holy Spirit, and to keep themselves in the love of God. The mercy shown to doubters comes from people doing that work themselves. It does not require anyone to pretend they have never wavered.
So doubting your faith does not put you outside the reach of God or His people. It does mean you should not be alone with it. Doubt kept private tends to harden into distance. Doubt brought into the open, to people who will be merciful, is often where faith grows deeper roots.
Today, tell one mature believer you trust about the specific doubt you have been carrying. Skip the vague admission that you struggle sometimes and name the actual question. If you are on the other side of that conversation, hear the whole question before you answer, and do not treat the person as a threat. Jude would call that mercy.