The two must always be mingled, in our feelings the Holy Spirit and our sin and imperfection. Our case must be like that of a sick man who is in the hands of the physician; presently he will be better. Therefore let no one think: Such a one possesses the Holy Spirit, consequently he must be altogether strong, without infirmities, and do only precious works. No, not yet.
The Gospel is not a proclamation for everybody. It is a proclamation exceedingly gracious, but a coarse, hard heart may hear it without receiving any good; rather are such made more audacious and careless, imagining they need not war against the flesh, because they do not feel their sin and misery. The Holy Spirit is given to none except to those who are in sorrow and fear; in them it produces good fruit. This gift is so precious and worthy that God does not cast it before dogs. Though the unrepentant discover it themselves, hearing it preached, they devour it and know not what they devour. The hearts which receive it with profit are such as feel their evil lust but are unable to escape from it. There must be struggling if the Holy Spirit is to abide in the heart, and let no one dare think it will be
Luther, Sermon for Pentecost, complete Sermons, Vol. 2, 281-282.