I know your works, that you are neither cold nor hot. I wish you were cold or hot. So then, because you are lukewarm, and neither cold nor hot, I will spit you out of My mouth.Revelation 3:15–16 — Modern English Version (Thinline Edition.; Lake Mary, FL: Passio, 2014)
Jesus is speaking to the church at Laodicea. His indictment of their works as a body is lukewarm. And if that is continued, the church would wither away.
This is not an indictment or a judgment on any Christian. It doesn’t mean that any of those Christians in the church lost their salvation. In fact, it has nothing to do with salvation. Nor does it have anything to do with individual behavior, even though the church as a body is made up of individuals.
It is a judgment on a church body.
A Christian doesn’t lose his salvation, neither do his works have anything to do with his salvation, whether helping it or not. In fact, good behavior isn’t fruit-bearing that Jesus looks for in a person. It can lead to it, and make it more bountiful, but bearing fruit is not the same as obeying the law.