"To the angel of the church in Laodicea write: These are the words of the Amen, the faithful and true witness, the ruler of God's creation. I know your deeds, that you are neither cold nor hot. I wish you were either one or the other! So, because you are lukewarm--neither hot nor cold--I am about to spit you out of my mouth. (Revelation 3:14-16 NIV)
One of the most dangerous teachings that the church has propagated over the last several centuries is the idea that once we are saved, we cannot lose that salvation. God warns us otherwise.
He tells the church in Laodicea that he is about to "spit" them out. At this point in church history there were no church buildings. There were no doubts what the word "church" meant. He was referring to the group of people who believed Jesus is the Christ, proclaimed Jesus as Lord, and experienced fellowship of the Holy Spirit. They were Christians...whom God was going to spit out.
That's not the only warning He gives us, His followers:
Dear friends, if we deliberately continue sinning after we have received knowledge of the truth, there is no longer any sacrifice that will cover these sins. There is only the terrible expectation of God's judgment and the raging fire that will consume His enemies. For anyone who refused to obey the law of Moses was put to death without mercy on the testimony of two or three witnesses. Just think how much worse the punishment will be for those who have trampled on the Son of God, and have treated the blood of the covenant, which made us holy, as if it were common and unholy, and have insulted and disdained the Holy Spirit who brings God's mercy to us. For we know the One who said, "I will take revenge. I will pay them back." He also said, "The LORD will judge His own people." It is a terrible thing to fall into the hands of the living God. (Hebrews 10:26-31 NLT)
Lukewarm living is dangerous. You never know how long God's patience will last before He decides to "spit out" even His own people. It's not good enough to simply proclaim Jesus as Lord. It never was. Lordship means, by definition, that He is in charge, He calls the shots, and that we follow Him. Anything less would be considered insubordination, going AWOL, or even...lukewarm.