Remember therefore how thou hast received and heard, and hold fast, and repent. If therefore thou shalt not watch, I will come on thee as a thief, and thou shalt not know what hour I will come upon thee.

Remember therefore how thou hast received and didst hear; and keep it , and repent. If therefore thou shalt not watch, I will come as a thief, and thou shalt not know what hour I will come upon thee.

Have in mind therefore in what manner thou hast received and heard: and observe, and do penance. If then thou shalt not watch, I will come to thee as a thief, and thou shalt not know at what hour I will come to thee.

'Remember, then, how thou hast received, and heard, and be keeping, and reform: if, then, thou mayest not watch, I will come upon thee as a thief, and thou mayest not know what hour I will come upon thee.

Be mindful, therefore, of the lessons you have received and heard. Continually lay them to heart, and repent. If, however, you fail to rouse yourself and keep awake, I shall come upon you suddenly like a thief, and you will certainly not know the hour at which I shall come to judge you.

Keep in mind, then, the teaching which was given to you, and be ruled by it and have a change of heart. If then you do not keep watch, I will come like a thief, and you will have no knowledge of the hour when I will come on you.

Remember therefore how you have received and heard. Keep it, and repent. If therefore you do not wake up, I will come as a thief, and you won't know what hour I will come to you.

Therefore, keep in mind the way that you have received and heard, and then observe it and repent. But if you will not be vigilant, I will come to you like a thief, and you will not know at what hour I will come to you.

Therefore remember what you have received and heard, and lay it to heart and repent. Unless you are on the watch, I will come like a thief, and you will not know at what hour I am coming to you.

Remember therefore how thou hast received - This may refer either to some uniqueness in the manner in which the gospel was conveyed to them - as, By the labors of the apostles, and by the remarkable effusions of the Holy Spirit; or to the ardor and love with which they embraced it; or to the greatness of the favors and privileges conferred on them; or to their own understanding of what the gospel required, when they were converted. It is not possible to determined in which sense the language is used; but the general idea is plain, that there was something marked and unusual in the way in which they had been led to embrace the gospel, and that it was highly proper in these circumstances to look back to the days when they gave themselves to Christ. It is always well for Christians to call to remembrance the "day of their espousals," and their views and feelings when they gave their hearts to the Saviour, and to compare those views with their present condition, especially if their conversion was marked by anything unusual.
And heard - How thou didst hear the gospel in former times; that is, with what earnestness and attention thou didst embrace it. This would rather seem to imply that the reference in the whole passage is to the fact that they embraced the gospel with great ardor and zeal.
And hold fast -
(1) Hold fast the truths which thou didst then receive;
(2) hold fast what remains of true religion among you.
And repent - Repent in regard to all that in which you have departed from your views and feelings when you embraced the gospel.
If therefore thou shalt not watch - The speaker evidently supposed that it was possible that they would not regard the warning; that they would presume that they would be safe if they refused to give heed to it, or, that by mere inattention and indifference they might suffer the warning to pass by unheeded. Similar results have been so common in the world as to make such a supposition not improbable, and to make proper, in other cases as well as that, the solemn threatening that he would come suddenly upon them.
I will come on thee as a thief - In a sudden and unexpected manner. See the notes on 1-Thessalonians 5:2.
And ye shall not know what hour I will come upon thee - You shall not know beforehand; you shall have no warning of my immediate approach. This is often the way in which God comes to people in his heavy judgments. Long beforehand, he admonishes us, indeed, of what must be the consequences of a course of sin, and warns us to turn from it; but when sinners refuse to attend to his warning, and still walk in the way of evil, he comes suddenly, and cuts them down. Every man who is warned of the evil of his course, and who refuses or neglects to repent, has reason to believe that God will come suddenly in his wrath, and call him to his bar, Proverbs 29:1. No such man can presume on impunity; no one who is warned of his guilt and danger can feel that he is for one moment safe. No one can have any basis of calculation that he will be spared; no one can flatter himself with any probable anticipation that he will have time to repent when God comes to take him away. Benevolence has done its appropriate work in warning him - how can the Great Judge of all be to blame, if he comes then, and suddenly cuts the sinner off?

Remember - Enter into a serious consideration of your state.
How thou hast received - With what joy, zeal, and gladness ye heard the Gospel of Christ when first preached to you.
Hold fast - Those good desires and heavenly influences which still remain.
And repent - Be humbled before God, because ye have not been workers together with him, but have received much of his grace in vain.
If therefore thou shalt not watch - If you do not consider your ways, watching against sin, and for opportunities to receive and do good.
I will come on thee as a thief - As the thief comes when he is not expected, so will I come upon you if ye be not watchful, and cut you off from life and hope.

Remember, therefore, how thou hast received and heard,.... That is, hast received upon hearing; for hearing goes first, and then receiving: the design of the advice is to put this church in mind of the doctrines of grace she had heard at the beginning of the Reformation, from Luther and others; such as justification by the righteousness of Christ, pardon through his blood, and atonement by his sacrifice, doctrines now almost lost and buried in forgetfulness; wherefore Christ would have her remember these things; how that she heard them with attention, reverence, humility, and without prejudice; and with much affection, so as to approve and love them, believe them, feel the power of them, and taste the goodness in them; and how she received them with all meekness, readiness, and joy, when now they are greatly disliked and rejected by many; very few attend to the doctrines of the Reformation. This is exactly our case:
and hold fast; the above doctrines, though the majority is against them, and learned men despise them, and they are charged with enthusiasm and licentiousness. It looks as if there was danger, as there is, that they would be entirely wrested out of her hands:
and repent: of her deadness, coldness, and indifference to these truths; of her unwatchfulness over them, and imperfection in them; not carrying truth to its fulness and perfection, resting in her first light and knowledge, and even going back from that:
if therefore thou shalt not watch: and preserve truth, and hold fast the form of sound words, and keep to the order, as well as the faith of the Gospel, and constantly attend divine worship, and look for the coming and kingdom of Christ:
I will come on thee as a thief; in the night, and at unawares, unthought of, and unexpected; which must be understood of coming to her in a way of rebuke and chastisement, by bringing some affliction, or suffering some sore distress to fall upon her: the phrase, "on thee", is left out in the Alexandrian copy and in the Ethiopic version:
and thou shalt not know what hour I will come upon thee: which, though applicable to the spiritual coming of Christ in the next church state, and to his second coming in his kingdom and glory, which will be both sudden and unexpected, yet these will be to the joy and comfort of the church; whereas what is here spoken is by way of threatening, and must relate to some severe dispensation on her; and which we might now justly expect, were we not in the unwatchful, unthoughtful, and ignorant situation here described.

how thou hast received-- (Colossians 2:6; 1-Thessalonians 4:1; 1-Timothy 6:20). What Sardis is to "remember" is, not how joyfully she had received originally the Gospel message, but how the precious deposit was committed to her originally, so that she could not say, she had not "received and heard" it. The Greek is not aorist (as in Revelation 2:4, as to Ephesus, "Thou didst leave thy first love"), but "thou hast received" (perfect), and still hast the permanent deposit of doctrine committed to thee. The word "keep" (so the Greek is for English Version, "hold fast") which follows, accords with this sense. "Keep" or observe the commandment which thou hast received and didst hear.
heard--Greek aorist, "didst hear," namely, when the Gospel doctrine was committed to thee. TRENCH explains "how," with what demonstration of the Spirit and power from Christ's ambassadors the truth came to you, and how heartily and zealously you at first received it. Similarly BENGEL, "Regard to her former character (how it once stood) ought to guard Sardis against the future hour, whatsoever it shall be, proving fatal to her." But it is not likely that the Spirit repeats the same exhortation virtually to Sardis as to Ephesus.
If therefore--seeing thou art so warned, if, nevertheless, &c.
come on thee as a thief--in special judgment on thee as a Church, with the same stealthiness and as unexpectedly as shall be My visible second coming. As the thief gives no notice of his approach. Christ applies the language which in its fullest sense describes His second coming, to describe His coming in special judgments on churches and states (as Jerusalem, Matthew. 24:4-28) these special judgments being anticipatory earnests of that great last coming. "The last day is hidden from us, that every day may be observed by us" [AUGUSTINE]. Twice Christ in the days of His flesh spake the same words (Matthew 24:42-43; Luke 12:39-40); and so deeply had His words been engraven on the minds of the apostles that they are often repeated in their writings (Revelation 16:15; 1-Thessalonians 5:2, 1-Thessalonians 5:4, 1-Thessalonians 5:6; 2-Peter 3:10). The Greek proverb was that "the feet of the avenging deities are shod with wool," expressing the noiseless approach of the divine judgments, and their possible nearness at the moment when they were supposed the farthest off [TRENCH].

Remember how - Humbly, zealously, seriously. Thou didst receive the grace of God once, and hear - His word. And hold fast - The grace thou hast received. And repent - According to the word thou hast heard.