I really appreciated the post by Kevin DeYoung “Is Sanctification Monergistic or Synergistic? A Reformed Survey”. He concludes, as do I, that “sanctification is both a gracious gift of God and it requires our active cooperation…these two truths are also eminently Reformed.” I recall a few years back that someone noted that I could not be Reformed in my theology and maintain that the Christian life consists of God’s activity and ours. It was my contention then and now that this is a misunderstanding of the Reformed tradition. DeYoung’s survey of Reformed theologies supports this.
See my “Our Strength, His Power: Who We Are and Why It Matters”. An excerpt:
Sanctification is not monergistic (involving one agent only) but synergistic (involving two or more agents). Augustine says it best, “Without God we cannot; without us God will not.” In some sense, every command issued to believers to live a holy life assumes we have the capability to carry out that command (2 Cor 7:1; 1 Thess 4:3-4; Heb 12:1; 1 Pt 1:15- 16). Yet, Scripture also insists that it is God who, by his grace, initializes and accomplishes everything that is holy in us (1 Cor 15:10; Col 1:28-29). Just as no one can take credit for their salvation, so no one can take credit for their sanctification. The same grace that saved us is the same grace that sanctifies us. At the end of the day, it is God alone who gets the glory for any spiritual progress made, though we are privileged to participate in the process….Behind every New Testament imperative issued to believers (i.e., command) is the assumption that God’s Spirit is present in us to empower our will to act. It is by the Holy Spirit’s strength that we fulfill God’s righteous requirements for holy living (Rom 8:3-4; 13-14). In fact, without the Spirit’s presence one cannot be a genuine believer (Rom 8:9), much less fulfill the requirements God issues to us. The Spirit of God is the presence of God in us and where God’s presence is, so too is his power to live for him!