‘For you were once darkness, but now you are light in Yehovah. Walk as children of light.’ Ephesians 5:8 (NIVUK)
This verse describes the essential change of nature which happens at salvation. Notice that it doesn't say you were in darkness; it says you were darkness. Darkness was your nature, your very essence, as an unbeliever. Nor does it say you are now in the light; it says you are light. Yehovah changed your basic nature from darkness to light. Your new nature is already determined. Why do you need the nature of Yeshua within you? So you can be like Yeshua, not just act like Him. Yehovah has not given you the power to imitate Him; rather He has given you a new nature, so that you can actually be like Him. You don't become a believer in Yeshua by acting like one. Yehovah doesn't measure your performance, or expect you to reach His standards. He knows you can't solve the problem of an old sinful self by simply improving your behaviour. He must change your nature; give you an entirely new self ? the life of Yeshua in you. That was the point of Yeshua' message in the Sermon on the Mount: 'For I say to you, that unless your righteousness exceeds the righteousness of the scribes and Pharisees, you will by no means enter the kingdom of heaven'. (Matthew 5:20). The scribes and Pharisees were the religious perfectionists of their day. They had external behaviour down to a science, but their hearts were far from Him. Yeshua wants to change people from the inside out, by giving them a brand-new nature and identity. Only after He changes you will you be able to change your behaviour. Choose to walk as a child of light today.