The following quote is from the end of John Stott’s commentary on Ephesians 5:18-21 (I think it’s also in his book Baptism and Fullness). Most of it is on the cutting room floor for my sermon on “Filled with the Holy Spirit”. Still worth a read.
We need now to return to the imperative on which these four participles depend, that is, to the Christian duty and privilege from which these four Christian attitudes result. It is the command Be filled with the Spirit. The exact form of the verb pl?rousthe is suggestive.
First, it is in the imperative mood. ‘Be filled’ is not a tentative proposal, but an authoritative command. We have no more liberty to avoid this responsibility than the many others which surround it in Ephesians. To be filled with the Spirit is obligatory, not optional.
Secondly, it is in the plural form. In other words, it is addressed to the whole Christian community. None of us is to get drunk; all of us are to be Spirit-filled. The fullness of the Spirit is not an élitist privilege, but available for all the people of God.
Thirdly, it is in the passive voice. NEB renders it: ‘Let the Holy Spirit fill you’. There is no technique to learn and no formula to recite. What is essential is such a penitent turning from what grieves the Holy Spirit and such a believing openness to him that nothing hinders him from filling us. It is significant that the parallel passage in Colossians reads not ‘Let the Spirit fill you’ but ‘Let the word of Christ dwell in you richly’ (3:16). We must never separate the Spirit and the Word. To obey the Word and to surrender to the Spirit are virtually identical.
Fourthly, it is in the present tense. In Greek there are two kinds of imperative, an aorist describing a single action, and a present when the action is continuous. Thus, when Jesus said during the wedding reception at Cana, ‘Fill the jars with water’ (Jn. 2:7), the imperative is aorist, since the jars were to be filled only once. But when Paul says to us, ‘Be filled with the Spirit’, he uses a present imperative, implying that we are to go on being filled. For the fullness of the Spirit is not a once-for-all experience which we can never lose, but a privilege to be renewed continuously by continuous believing and obedient appropriation. We have been ‘sealed’ with the Spirit once and for all; we need to be filled with the Spirit and go on being filled every day and every moment of the day.
Here, then, is a message for both the defeated and the complacent, that is, for Christians at opposite ends of the spiritual spectrum. To the defeated Paul would say, ‘Be filled with the Spirit, and he will give you a new love, joy, peace, patience, kindness, goodness, faithfulness, meekness and self-control.’ To the complacent Paul would say ‘go on being filled with the Spirit. Thank God for what he has given you thus far. But do not say you have arrived. For there is more, much more, yet to come.’
Stott, J. R. W. (1979). God’s new society : The message of Ephesians (208–209). Downers Grove, Ill.: InterVarsity Press.