People are incapable of understanding spiritual concepts, especially when they have a weak or modest desire and low motivation for learning spiritual concepts. Therefore, in order to overcome this self-imposed handicap, parables or illustrations which are drawn from common day-to-day life, are used in order to teach spiritual concepts.
Infirmity of the flesh, refers to the weakness or feebleness of one’s ability to understand.
Remember, there are two environments in which you can live your life.
The first environment is that of the sin nature, which establishes and promotes an inherent weakness, both physical and mental, for living and functioning within ones life. Terms such as darkness or fog, are used to describe human weaknesses and inability to understand, perceive, and connect with reality.
The second environment is that of the spiritual life, which establishes and promotes inherent strengths, both physical and mental, for living and functioning within ones life. Terms such is light or discernment, are used to describe human abilities to see and perceive reality, as it really is.
The infirmity of the flesh, refers to the weaknesses established within the sin nature environment, which prevents understanding, and in order to overcome that barrier, illustrations from common day-to-day life are used to illustrate spiritual concepts.
Paul has been using the master and slave relationship, to describe our limitations and restrictions that we face in life.
Under the sin nature, which is a life we had apart from salvation, we were severely restricted, with no rights whatsoever.
And under that sin nature environment, we lived within the rules of the sin nature, with our only capability was that of producing sin. Here, sin refers to every thought and action that occurs within the sin nature environment. And so the phrase, slaves to impurity and to lawlessness leading to more lawlessness, simply describes the trap of the sin nature environment. In other words, we are trapped within the sin environment, and therefore, you can only produce sin.
Furthermore, when you are living within the sin nature environment, and think nothing of it, or do not know any better, then your life within that environment, seems natural, and you actively promote and pursue thoughts and activities within that environment.
This is why, false religions, for example, become so successful with a dedicated following of people.
On the other hand, when saved, then you have an opportunity to escape the sin nature environment, and live within the spiritual life environment. And having that better opportunity, as Paul states here, you should pursue that spiritual life with equal or more enthusiasm, and determination, then you did with the former environment.
And this is where Christianity falters.
Most Christians, do not understand Christianity, because they do not learn the differences between these two patterns of life. And the learning is lacking, because the desire to learn is lacking.
Lawlessness leading to more lawlessness, is the same as failure leading to more failure, or loss leading to more loss, or nothingness leading to more nothingness.
Righteousness leading to sanctification, describes the spiritual life leading to spiritual growth. And growth in the spiritual life can only occur when you pursue it within the framework of the spiritual life. Namely, confession to gain access to the spiritual environment which we call fellowship, and a daily study of Bible doctrine within that fellowship sphere, in order to learn and understand, and then application of that understanding, which is your spiritual production, which promotes spiritual growth.
And this, results in the spiritual construction of your soul, and the enhancement of your entire existence. And that is, or should be, your objective and goal in life, so that you can have the greatest meaning and purpose of your life, for your life, for all of eternity.