To be lukewarm is to live as if what you presently know and experience of Christ is enough. No need or desire to press in further. No need or desire to seek after God. Little or no longing to pray and fast. Little or no longing to break free of sin. Satisfied with the current depth of delight in the Spirit. Satisfied with the current extent of knowledge of the Father.
from To the One Who Conquers: 50 Daily Meditations on the Seven Letters of Revelation 2-3 by Sam Storms