How can mankind redeemed by Messiah yet burdened with a sin-nature in the flesh obey Messiah’s command: Matthew 5:48 “Be ye therefore perfect, even as your Father which is in heaven is perfect.”

Christian response,

Though perfection is the goal in the Christian life, we know that we remain burdened with a sin-nature inherited from our father who ultimately inherited it from our first father, Adam (Romans 5:12); therefore, our New Nature in the Spirit struggles with our old nature in Adam and the Curse (Romans 7); therefore, perfection is a lofty goal but in practicality, not attainable while constrained by decaying flesh within the Realm of Time – BUT – we can attain the perfection and righteousness of Messiah imputed into and over our lives by grace (unmerited favor unattainable by human effort) through faith (trusting-believing) in Jesus as our Lord and Mediator for sin (2 Corinthians 5:21); it is Jesus and Him alone having been born of the hypostatic union (Philippians 2:8) and circumventing the sin-nature that permitted Him to observe the Law of Moses/the Decalogue in absolute perfection (Matthew 5:17) and thereby become our propitiation for sin; therefore, the one who trusts in Jesus as Lord receives Messiah’s perfection, just like that of the Father, imputed into and over their life; therefore, the one who trusts in Jesus is spiritually and positionally “right” before the Father, forever via a Covenant of Grace established in Messiah’s innocent blood (Luke 22:20). Perfection remains the goal in the Christian life as we walk in sanctification via the indwelling Holy Spirit and His tutelage; this, as the Spirit prepares us for service in the New Jerusalem (1 John 2:27).