

Ephesians 6:18
Praying always with all prayer and supplication in the Spirit, and watching thereunto with all perseverance and supplication for all saints;
Having listed the pieces of armor, Paul closes the passage not with another piece to be strapped on but with the very breath and posture by which the whole armor is put to use: praying always. Yet even here right division matters, for prayer under the kingdom program addressed to Israel carried its own pattern and its own conditions, bound up with an earthly people, an earthly hope, and often earthly petitions for deliverance from enemies, vindication, and the coming of the kingdom, as in the model Christ gave the twelve, thy kingdom come (Matthew 6:10). The prayer Paul commends to the Body of Christ flows instead out of the standing already established in the mystery: for through him we both have access by one Spirit unto the Father (Ephesians 2:18), and in whom we have boldness and access with confidence by the faith of him (Ephesians 3:12). This is access granted on the ground of a finished redemption, not a plea for a kingdom yet to come, nor dependent on the sign gifts or ecstatic manifestations that once accompanied Israel's transitional program in the earlier chapters of Acts.
Praying in the Spirit, then, does not describe some ecstatic utterance or sign, but praying according to the mind of the Spirit as revealed in sound doctrine, in keeping with the pattern Paul elsewhere gives, I will pray with the spirit, and I will pray with the understanding also (1 Corinthians 14:15), and the Spirit itself maketh intercession for us with groanings which cannot be uttered... because he maketh intercession for the saints according to the will of God (Romans 8:26-27). It is prayer shaped by the truth just girded on, offered from a heart already secured by imputed righteousness, a mind already settled by the hope of salvation, and it takes up its true weapon, the sword of the Spirit, which is the word of God (Ephesians 6:17), as its content and confidence rather than groping after signs or feelings. Paul's own prayers recorded for these churches, that ye may be filled with all the fulness of God (Ephesians 3:19), that ye may know what is the hope of his calling (Ephesians 1:18), give the pattern: not petitions for an earthly kingdom's arrival but for growth in the knowledge of the mystery already granted.
Practically, this means the saint's prayer life in this dispensation of grace is marked by continual dependence, always, not fitful or occasional, and by intercession for all saints, reaching beyond one's own need to the whole Body. It is watching thereunto with all perseverance, a soldier's alertness carried into prayer, for Paul asks the same for himself, that utterance may be given unto me, that I may open my mouth boldly, to make known the mystery of the gospel, for which I am an ambassador in bonds (Ephesians 6:19-20). Prayer, understood this way, is not a separate seventh piece of armor but the very act of standing in all the rest, girded, breastplated, shod, shielded, and helmeted, and lifting that whole equipped man continually to the Father through the one access grace has secured, that having done all, he may stand (Ephesians 6:13).