Revelation 3:1-6
1 And to the angel of the church in Sardis write,
"These things says He who has the seven Spirits of God and the seven stars:
'I know your works, that you have a name that you are alive, but you are dead. 2 Be watchful, and strengthen the things which remain, that are ready to die, for I have not found your works perfect before God. 3 Remember therefore how you have received and heard; hold fast and repent. Therefore if you will not watch, I will come upon you as a thief, and you will not know what hour I will come upon you. 4 You have a few names even in Sardis who have not defiled their garments; and they shall walk with Me in white, for they are worthy. 5 He who overcomes shall be clothed in white garments, and I will not blot out his name from the Book of Life; but I will confess his name before My Father and before His angels.
6 He who has an ear, let him hear what the Spirit says to the churches.' "
There are many churches that started out preaching truth and righteousness but, for whatever reason--apathy, declining attendance, a desire to fill pews--have begun to water down the message, and have embraced to things of the world, and have shut out the possibility that we can know the truth. They do this in a effort to be "seeker-friendly". They do this so they don't ofennnnd people. They seem to use one particular type of Bible. They call themselves a "church", they call themselves "Christian". Yet the things they teach are not simply doctrinal errors. The things they teach are damnable heresies--that the Cross of Christ is not the only means of salvation; that "God loves you just the way you are and He has a wonderful plan for your life"; that you can say a little prayer, get dunked in water, go an with your life as if nothing happened, but by golly you're saved! These are those who "have a name that they are alive", but in that they have strayed from the narrow way, have led many to death. They may do good works, but these works are not done in righteousness, therefore they are not acceptable to God.
They must remember their roots--how they started off in the truth. They need to understand and listen to those "who have not defiled their garments"--those will be saved in spite of their association with these bodies--and strengthen those who have remained steadfsat in their faith. If they do this, and repent from their departure from the truth, then Jesus will show mercy on them. Otherwise, I hate to think of what will happen to these churches.
If they do not repent, then Christ--the Head of the church--will come upon them--at an hour they do not expect--and even that righteousness they think they possess will be taken from them (Luke 19:26).