All Christians agree that God's Word to us in Sacred Scripture makes one truth abundantly clear: God loves us, and He sent His only son, Jesus Christ, to die for our sins so that we might enter the kingdom of Heaven (John 3:16, 1 John 4:9); and He desires for us to "abide in His love," to love Him and to love one another (John 15:9).
We see the call to imitate the love of God over and over again in His Word. "Be perfect, therefore, as your heavenly Father is perfect." (Matthew 5:48) "Anyone who does not take up his cross and follow me cannot be my disciple." (Luke 14:27) "Love one another as I have loved you." (John 15:12) "Be imitators of God, therefore, as dearly beloved children." (Ephesians 5:1)
God's love for us is perfect. He asks us to imitate His love. Thus we are asked to love perfectly - and yet some people argue that as Christians, we need not strive for perfection in love.
There are no new heresies, and when we hear what certain Christians have to say about the call to perfect charity, we hear the 21st-century versions of some of the oldest heresies in the book. The first, which smacks of the doctrine of "total depravity" embraced by Luther and Calvin, deems the perfection of our human love impossible, even with the help of God's grace. The second is much akin to Jansenism, which encouraged its adherents to set an example of rigorous piety and moral behavior. It argues that perfection in love is naturally possible, or that as humans, we can work to achieve it, presumably without the help of God's grace.
The latter heresy is easily refuted. We know that God's grace is necessary if we wish to amend our lives, and is therefore necessary for our perfection. Apart from Him we can do nothing (John 15:5). We say with St. Paul, "By the grace of God I am what I am, and His grace to me was not without effect" (1 Corinthians 15:9-11). That said, let's focus on the former - the denial of the possibility of perfection in love.
Many of the ideas set forth by Protestant author Brennan Manning, a former Franciscan priest, in his book The Ragamuffin Gospel, are prime examples of this denial. While Manning has no qualms about quoting the saints and using Latin phrases here and there throughout the book, he clearly harbors bitterness toward the Church, specifically towards the emphasis Catholic theology places on the call to perfect love and holiness.
"The gospel declares that no matter how dutiful and prayerful we are, we cannot save ourselves," Manning writes (p. 79). It's true that we cannot save ourselves, but dutifulness and prayerfulness are attitudes that constitute a proper response to the gift of our salvation. We prove we are Christ's disciples not by remaining as we are but by "bearing much fruit" (John 15:8).
In reference to Christ's teaching that we must be "like little children" (Matthew 18:2-4), Manning writes:
"The kingdom belongs to people who aren't trying to look good or impress anybody, even themselves. They are not plotting how they can call attention to themselves, worrying about how their actions will be interpreted or wondering if they will get gold stars for their behavior. Twenty centuries later, Jesus speaks pointedly to the preening ascetic trapped in the fatal narcissism of spiritual perfectionism... The child doesn't have to struggle to get himself in a good position for having a relationship with God... He doesn't have to create a pretty face for himself; he doesn't have to achieve any state of spiritual feeling or intellectual understanding. All he has to do is happily accept... the gift of the kingdom." (p. 53)
And yet our relationship with God demands by definition that we do more than "happily accept the gift of the kingdom" - it demands that we take up our cross and follow His Son: "Anyone who does not take up his cross and follow me cannot be my disciple" (Luke 14:27). It demands that we suffer with Christ. How do we suffer with Christ if not by striving to "avoid the near occasion of sin" and to love more perfectly? The journey towards perfection in love is arduous, but it is the path set before every Christian: the path to sainthood.
In 2 Corinthians 9:8, St. Paul reminds us that God will give us the grace to accomplish whatever good work we attempt: "God is able to make all grace abound to you, so that in all things at all times, having all that you need, you will abound in every good work." If God's grace makes all works of charity possible, who are we to dismiss perfection in charity as an impossibility? It is as St. Teresa of Avila writes in her Meditations on the Song of Songs: "Many remain at the foot of the mount who could ascend to the top... I repeat and ask that you always have courageous thoughts. As a result of them the Lord will give you grace for courageous deeds."
We know that we are free to pursue perfection because the Church teaches that we retain our free will even in our sinfulness. "By our first parents' sin, the devil has acquired a certain domination over man, even though man remains free" (Catechism of the Catholic Church 407). In the light of this truth, the rejection of the possibility of perfection in love - the heresy of total depravity - is ultimately a denial of our free will. It gives Satan far too much credit, and in its attempt to highlight our great need of God's grace, it actually fails to acknowledge the full extent to which God's grace can sanctify us.
I'll leave you with a passage from C. S. Lewis' The Four Loves, from the chapter about Charity, that says more beautifully what I have been trying to say all this time:
"God, who needs nothing, loves into existence wholly superfluous creatures in order that He may love and perfect them. He creates the universe, already foreseeing - or should we say 'seeing'? there are no tenses in God - the buzzing cloud of flies about the cross, the flayed back pressed against the uneven stake, the nails driven through the mesial nerves, the repeated incipient suffocation as the body droops... Herein is love. This is the diagram of Love Himself, the inventor of all loves." (p. 127)