This coming Sunday is Pentecost, the day in which we celebrate what might be the highest point in Christian theology: the coming of the Holy Spirit to live in the hearts of men; the deification of the human person, the end towards which all of Christ's salvific work was oriented. This is what Christianity is ultimately about: God living in the heart of a man and transforming him through his presence.
The church I attend is Romanian Pentecostal -- perhaps a surprise, given some of the things I post about on here! In my experience, the Holy Spirit is associated in the Romanian Pentecostal's mind with ecstatic experiences and the loss of agency. Speaking in tongues happens spontaneously, and the person doesn't know what is being said as it is happening. Prophetic utterances arise spontaneously as well, as God chooses to use some person to communicate an unpremeditated message.
It would be a mistake, however, to limit the role of the Holy Spirit in our life to these sorts of special encounters and events. On the contrary, the Spirit is involved in our every-day life just as much; he is present in each of the little choices we make throughout the day. Consider what the Apostle Paul says:
Live by the Spirit, I say, and do not gratify the desires of the flesh. For what the flesh desires is opposed to the Spirit, and what the Spirit desires is opposed to the flesh (Gal 5.16-7).
Far from being limited to momentary losses of control over ourselves, the Spirit is present in the choices we make every day. Indeed, every day we face a choice either to live by the Spirit, or else to live by the flesh. Because we have this choice, therefore we are given the injunction: Live by the Spirit and do not gratify the desires of the flesh. These two options stand before us, and so we are called to choose the one and not the other. In a manner similar to the injunctions in Deut 30: See, I have brought before you life and prosperity, death and adversity. . . Choose life so that you and your descendants may live (vv. 15, 19).
What does it mean to live by the Spirit? And what does it mean to live by the flesh? The way I understand it, Paul seems to describe two different impulses within us, and the choices we make to some extent determine which will take over our personalities:
Now the works of the flesh are obvious: fornication, impurity, licentiousness, idolatry, sorcery, enmities, strife, jealousy, anger, quarrels, dissensions, factions, envy, drunkenness, carousing, and things like these. . . . By contrast, the fruit of the Spirit is love, joy, peace, patience, kindness, generosity, faithfulness, gentleness, and self-control (vv. 19-21, 22-3).
What kind of a life are you living? From which fountain do you draw, when you live your day-to-day life? If we draw from the flesh and live according to it, we see the sorts of things that we end up doing. We are turned against each other and against ourselves, we have dealings with evil spirits, and we put up false gods for ourselves. On the contrary, to live according to the Spirit is to act always for the good. That's the sort of person we turn into when God is within us, and that is how God shows us what he is like: his presence in us transforms us into his image, which is one of unbounded goodness!
More often than not, I end up living in the flesh. I notice it, and I don't always do much about it. But Paul's injunction stands before me: live according to the Spirit! Make your choice today about how you are going to live, where you will draw your strength, and whom you will serve. Don't expect that God will simply "zap" holiness into you and you will be instantly transformed. I am discovering that we have to make the difficult choice to live according to the Spirit every day, making progress by baby steps if at all.
The choice to live by the flesh is one with catastrophic consequences: I am warning you, as I warned you before: those who do [according to the flesh] will not inherit the kingdom of God (v. 21). In the kingdom of God, where human persons are transformed into the divine likeness, a son of the devil has no place. There is no place in the people of God for those who will kill, destroy, hate, steal, and consult with devils. These things have to be purged from us, and God gives his Spirit for this end.
Do not be deceived; God is not mocked, for you reap whatever you sow. If you sow to your own flesh, you will reap corruption from the flesh; but if you sow to the Spirit, you will reap eternal life from the Spirit. So let us not grow weary in doing what is right, for we will reap at harvest time, if we do not give up. So then, whenever we have an opportunity, let us work for the good of all, and especially for those of the family of faith (6.7-10).
Once again we see that living according to the Spirit means acting for the good of all.