Therefore you shall be perfect, just as your Father in heaven is perfect.  (Matthew 5:48)

Albert Barnes in his commentary on Matthew 5:48 states: 

The Saviour concludes this part of the discourse by commanding his disciples to be “perfect.”  This word commonly means“finished, complete, pure, holy.”  Originally, it is applied to a piece of mechanism, as a machine that is complete in its parts.  Applied to people, it refers to completeness of parts, or perfection, where no part is defective or wanting.  Thus, Job (Job1:1) is said to be “perfect;” that is, not holy as God, or “sinless” – for fault is afterward found with him (Job 9:20; Job42:6); but his piety was “proportionate” – had a completeness of parts was consistent and regular.  He exhibited his religion as a prince, a father, an individual, a benefactor of the poor.  He was not merely a pious man in one place, but uniformly.  He was consistent everywhere…. This is the meaning in Matthew.  Be not religious merely in loving your friends and neighbors, but let your piety be shown in loving your enemies; imitate God; let your piety be “complete, proportionate, regular.”  This every Christian may be; this every Christian must be. 

Thy beauty of teleios is the idea that all our areas of imperfection can be fixed.  God desires to make us complete and has our finished perfection in view.  We can live the Sermon on the Mount and we live it by the teleios life.  It is commanded and we have no reason but to obey to the command.  What is holding you back from the process of completeness?

To be incomplete is not God’s plan, but our choice.