Therefore, 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 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];

So, beloved, since you are looking forward to these things, be diligent and make every effort to be found by Him [at His return] spotless and blameless, in peace [that is, inwardly calm with a sense of spiritual well-being and confidence, having lived a life of obedience to Him].