When speaking of grace, it is important to remember that we are all sinners. There will be times when we reflect the love of God and live the Christian life well, and there will be times when we err and show our human imperfections. When we are in a state of grace, we are living the deiform life on earth imperfectly but truly. For one to do this sanctifying grace must be received because it provides the theological edifice that supersedes our human nature (Hardon Ch.4)
This deiform life, as John Hardon describes it, starts with the sacrament of Baptism. This sacrament infuses us with sanctifying grace and elevates us to partake in the divine life. In Baptism, we are born again in the way the scriptures speak. We are “born again in a new childhood of true innocence” (Hardon Ch.4). With original sin, and all sin, washed away we now partake in the deiform life imperfectly but truly. How can this be? We still have concupiscence, and though we may not fall into mortal sin we will commit venial sin. This is one of the reasons why Jesus established the sacramental system. Our physical bodies require exercise, sleep, and proper nourishment to grow into healthy adults. It is very similar in our spiritual lives as we need prayer and nourishment through the sacraments to continue in the practice of virtue (Hardon, Ch.4).
There are many saints throughout history that can be used to illustrate the example of the deiform life that living in a state of grace can bring about, but I feel the need to use a personal example. The Director of Religious education of St. Francis De Sales in Tucson, Arizona fits this mold. I am a member of the parish, and Maureen and her husband Deacon Russ, have been mentors. Maureen has suffered from Multiple Sclerosis for many years and is often in great pain. However, she never complains and offers up her sufferings for the parish and the children that she is responsible for educating in the faith. Her life is an example of how living the Christian life can inspire someone else to do the same. She is involved in many other ministries, but no matter what is going on has the time to give an encouraging word, pray for someone, and answer questions about the faith. Her zeal to share the Gospel drives her and you can see grace at work in her life. Her life is a great example for those of us under her tutelage.
Hardon, John. History and Theology of Grace. Ann Arbor, MI: Sapientia Press, 2005.