“To the angel of the church in Sardis write: These are the words of him who holds the seven spirits of God and the seven stars. I know your deeds; you have a reputation of being alive, but you are dead. Wake up! Strengthen what remains and is about to die, for I have not found your deeds complete in the sight of my God. Remember, therefore, what you have received and heard; obey it, and repent. But if you do not wake up, I will come like a thief, and you will not know at what time I will come to you. Revelation 3:1-3

Are we outwardly religious but inwardly decaying? Here's a direct warning to us - the modern day church - who are similar in nature to the hypocritical people of the Church of Sardis.

Matthew Henry's Concise Commentary explains it in detail:

Hypocrisy, and lamentable decay in religion, are sins charged upon Sardis, by One who knew that church well, and all her works.

Outward things appeared well to men, but there was only the form of godliness, not the power; a name to live, not a principle of life.

There was great deadness in their souls, and in their services; numbers were wholly hypocrites, others were in a disordered and lifeless state.

Our Lord called upon them to be watchful against their enemies, and to be active and earnest in their duties; and to endeavor, in dependence on the grace of the Holy Spirit, to revive and strengthen the faith and spiritual affections of those yet alive to God, though in a declining state.

Christ enforces his counsel with a dreadful threatening if it should be despised. Yet our blessed Lord does not leave this sinful people without some encouragement.

He makes honorable mention of the faithful remnant in Sardis, he makes a gracious promise to them. He that overcomes shall be clothed in white raiment; the purity of grace shall be rewarded with the perfect purity of glory.

Sure a wake up call for some of us, myself including. Now the question is what are we going to do about it?