The Literal Greek reads ~ the souls of you having been purified by obedience to the truth unto brotherly love sincere out of (a) pure heart one another love. The emphasis being "having been purified" and having been purified is accomplished by obedience to the truth.
Our souls are made up of our mind, will, intellect and emotions. There is much work required to actually purify those realms and bring them into obedience to the truth.
James 3 tells us the wisdom of the world is of the earth, it is natural or sensual and when we are simply led by anything other than the Spirit and the word we are operating out of a place that is simply natural. Could we say it is mental, emotional or willful? When our soul is not governed, renewed or purified it can not be supernatural or spiritual.
Jesus told his disciples they were washed by the words he had spoken, John 15. You purify things that get defied or dirty. The word Hebrews tells us it is the word that separates between soul and spirit. It is the only safe dividing line we have.
How do I know if my thoughts or feelings are right? Only by measuring them according to the word. Do they lead me into Christ or into self? And there the rubber hits the road. The will of man comes into play and choices are required.
This verse shows us it is our obedience to the truth that leads us to a sincere brotherly love. This word sincere is made up of two words meaning not the hypocrite. It describes sincere behaviour free of hidden agendas. It is only by Holy Spirit working in our hearts giving us the grace to love that we can maintain pure souls and sincere love. Jude tells us to keep ourselves in the love of God by praying in the Spirit. So this too requires choices. I must move into the spirit and receive the grace that enables me to think right and act right. I choose love and mercy over judgment and condemnation.
The Father has many wonderful attributes, but God is love in it’s purest form. The fruit of love is seen in 1 Corinthians 13:4-8His love to us is worked in and through us that we might be patient and kind without envy and boasting. Not insisting on our own way free from being irritated or resentful. Rejoicing with the truth, bearing all things believing all things, hoping all things and enduring all things. For this love never fails and this love according to 2 Corinthians 5:14 controls us or as the literally Greek implies grips tightly with a sense of constraint and enables us to “earnestly love from a pure heart”.
Purified souls are washed and measured by our obedience to the truth for the purpose of holding ourselves in sincere love for the brethren. We are after pure souls and pure hearts. We can evaluate heart and soul by the fruit we produce.