2 Peter 1:10

10Therefore, believers, be all the more diligent to make certain about His calling and choosing you [be sure that your behavior reflects and confirms your relationship with God]; for by 1:10 I.e. developing the moral virtues outlined in vv 5-7.doing these things [actively developing these virtues], you will never stumble [in your spiritual growth and will live a life that leads others away from sin];