Orthodoxy comes first because the Law came first. Follow my thinking here, the Law was the schoolmaster that led us to Christ, Christ is the ultimate love, and therefore we cannot even understand love without right beliefs. Let’s use salvation the first and most important step in spiritual growth as the example. What good is my salvation without understanding just how wretched I am? The love that I experience from Christ is literally based on my understanding that I have sinned, God hates what I have done, and he will punish me. If I do not understand this, I can never really believe that I need Christ. If I do not believe I need Christ and that I am wretched without him, I am not saved. So, Orthodoxy, right belief, in my optioning is the first step. Ezekiel said “26And I will give you a new Heart, and a new spirit I will put within you. And I will remove the Heart of stone from your flesh and give you a Heart of flesh. 27 And I will put my Spirit within you, and cause you to walk in my statutes and be careful to obey my rules.” (Ezekiel 36: 26-27) and 1 Corinthians 13 says “I am nothing without Love”. These agree with this line of thought. In the case of Ezekiel 36 the person needs to understand or believe that they need God to put a new Heart in them or else why not just tell God “no thanks my current Heart is good enough”. With 1 Corinthians 13, I do not believe orthokardia (Love) and Agape (Love) are equitable. Agape is real love which is feeling, belief, and action. I would say that 1 Corinthians 13 is saying that if you do not have all three, Orthodoxy, Orthopraxy, and Orthokardia, you do not have an Agape love and that means you are nothing. In the end the conversation is tomato/”tamato”. If we are seeking God with all heart, mind, soul, and strength the beginning point is irrelevant because the Holy Spirit will make the end point heaven and oneness with God’s will. It is interesting that Jesus says Heart before mind.
I think biblically it can be established that orthopraxis is a result of orthodoxy. “Faith comes by hearing and hearing by the word of God”, Paul said (Romans 10:17).
Paul actually had a lot for say on this subject: “…but be transformed by the renewing of your mind…” (Romans 12:2), “Do your best to present yourself to God as one approved, a worker who does not need to be ashamed and who correctly handles the word of truth” (2 Timothy 2:15). “All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness,” (2 Timothy 3:16). For Paul orthodoxy was the correct handling/understanding of scripture and orthopraxis flowed from it. It really is a cyclical relationship, you have to have the right practice of prayer and study in order to development the depth in the word that Paul is talking about so orthopraxis leads to orthodoxy and orthodoxy leads to orthopraxis in an ever increasing cycle that is part sanctification for the individual.
I would conclude with saying that we should be very wary of any system that seeks to separate orthodoxy and orthopraxis. Scripture teaches them as two parts of the same process, one does not exist separate from the other.
Think about that.