Revelation 3:2

Be thou watchful, and establish the things that remain, which were ready to die: for I have found no works of thine perfected before my God.

Be thou watchful ... Many commentators love to tie this in with the repeated destruction of the city of Sardis through failure to "watch"; but this is not necessary. Christ himself, in the great discourse on Olivet (Matthew 24 and parallels), enjoined watchfulness; and that discourse is frequently in the mind of the writer throughout Revelation; and this is very likely the case here. See Mark 13:35,37.

Establish the things that remain ... This stresses a truth sometimes overlooked, namely, that even in dead, wicked, in different congregations there may be some members, probably humble and obscure, who are still trying to do the will of God and in their hearts grieve for the desolation. Barnes said, concerning such as these:

An important duty in a low and languishing state of religion, is to "strengthen the things that still survive." It is to cultivate all the graces that do exist; to nourish all the love of truth that may linger in the church; and to confirm, by warm exhortation, and by reference to the gracious promises of the word of God, the few who may be endeavoring to do their duty, and who, amidst many discouragements, are aiming to be faithful to the Saviour.[11]