Is holiness something we are in Christ or something we need to become? Though a foundation of holiness has been laid in us by virtue of the fact that we now are God’s possession, Scripture makes it clear that something is still missing. Time and again we are exhorted to live a holy life. And that means that the sins of the flesh must be forsaken.
There’s no question that living a holy life is expected. And if expected, it must be attainable (not the impossibility of being sin-free, but definitely that of being self-controlled). It’s the whole point of living a godly life. Attempting to please God by walking out our faith in a manner worthy of Him is not easy. It’s takes effort. But we need to remember that God has accepted us. Pleasing God is a whole lot different from trying to become acceptable to Him.
From Free from the Power of Sin: the Keys to Growing in God in Spite of Yourself