How can grace be proved to be effective if it does not cure constitution sins. The great promise is that grace shall change the nature of the wolf and lion, or the bear, the asp, the cockatrice, and that they shall become as lambs. But this is what grace can never do, if it does not change habitual patterns of life that arise from one's constitution. If grace, which is a habitual principle, does not change the inclination of constitution, then I don't know what it does. Outward occasions also give particular advantages to particular sins.
Some sins gain an advantage through education.
If we educate our children to be proud and self-sufficient we heap dry fuel upon them until such a time as their own lust will flame and destroy them. Also, different societal environments in life inflame particular sins. Brothers and sisters in Christ, I take it for granted that the vilest of the lusts which our Savior and His apostles warns us to mortify may be working in the hearts and minds of the best of us. A particular lust may be habitually prevalent, where, for a number of reasons, it never brings forth outward effects. If you find that your mind and soul is frequently and greatly pressed upon by a particular lust and corruption, know that this in itself does not prove that particular lust or corruption to be habitually dominant.