It is showing us that even as born-again believers, we can make lazy & foolish choices, not being dilligently watchful over our walks with God. The lack of “oil in our lamps” represents our failure to take our walk with God seriously, pulling back, ignoring the Holy Spirit, being spiritually lazy, and making foolish choices. It depicts a person who still entertains things God has said or advised not to. We may “think” we don’t have to be as dilligently watchful over our relationships with the Lord, but if we aren’t….we will experience the fruit of our actions. Preparing ourselves for the groom, is to allow & participate with Christ…letting Him reign & rule over our hearts, leading & guiding & teaching, so that we are being changed into the image of Christ. Just being born-again doesn’t make these changes, we have to particiapte & maintain our walks.