Sanctification is a work of God alone

"Men do not make themselves holy; neither their regeneration nor their growth in grace is due to their own diligence or obedience, but to God alone. The fruit of the Spirit - love, joy, peace, long suffering, kindness, goodness, faithfulness, gentleness, self-control - are just that, the fruit of the Spirit, not of ourselves, for it is Christ who lives in us, and it is Christ who works in us both to will and to do his good pleasure. We are commanded to 'work out' what God has already 'worked in' us. We cannot work out unless God works in us, for without Christ we can do nothing. We are Christ's workmanship, not our own." - John W. Robbins, Foreword to the First Ediction of What is the Christian Life?, Pg. 15