Summary: Any person without principles is a very dangerous person, so is any believer in Christ that walks without principles.
In the teaching of grace and principles there's no contradictions unless one would want to create those contradictions.
From the word go in a famous quotation grace itself works by or through given principles as we are going to see in the next passages.
In Ephesians 2:8-10 For by grace are you saved through faith; and that not of yourselves: it is the gift of God: Not of works, lest any man should boast. For we are his workmanship, created in Christ Jesus unto good works, which God has before ordained that we should walk in them...
If we want to find any contradictions about grace and principles especially for those who think principles are unnecesary if we are under grace, the contradiction is already found right in this very same most quoted scripture by by many.
If we examine verse 8-9 it shows us how no works are involved with salvation right? But the second part in verse 10 shows us that we are created in Christ towards good works not even just a while ago but which God ordained long ago before we even ever believed or ever existed on earth! One can choose to contradict with these verses, but there's no contradiction at all for sure. It's about how we understand the scriptures.
First of all we find that grace a lone without faith can't bring us to salvation. A mere saying we're saved by grace a lone without mentioning through faith will an error because it's impossible to please God without faith Hebrews 11:6. The ver accurate word is "You're saved By.., and then Through..," To simply this is to say the power that saves is grace, the channel through which it saves is faith. That's why we must note the word without faith it's impossible to please God, not without grace...in this passage what pleases God is our faith not his grace.
We must contribute something in return to reveal our acceptance and admission of our guilt, submission to his authority as the Lord in charger, that's it all begins by confessing him as lord, gratitude towards his plan love, honor towards his divine supreme lordship, and willingness to follow his instructions as the guidance father of a reckless soul. This is what many are failing to totally understand.
Our contribution or the response we should give towards the God of salvation in regards to his salvation plan, is not to show how good we are because no one is good, but rather to humble ourselves before him and resist every kind of evil that displease God James 4:7-10, learn from his word the things that our heavenly father is well pleased of, as he said to his son Jesus this is my son in whom I am well pleased Matthew 3:17, you may not be perfect in obedience as it's the battle of every soul, but try to obey his instruction 1 John 2:3-6.
That mere obedience and willingness to obey is what actually pleases God because it proves our faith and trust in God Proverbs 3:4-7. Obedience to the very hard instructions of God proves our very trust and dependency on God. Christ reminds us that there's no one good accept the father Mark 10:17. We therefore can't depend on our own goodness at all. Sometimes we may fail, but we must continue trusting God for the better through his Holy Spirit and grace that we will receive victory at the opportune time.
So then when we talk about obedience, we're not talking about our own goodness, but rather respect, honor, faith in the personality of God, consciousness about God's will and anything inline with this. Don''t ever let anyone mislead you by canning words that obedience to the principles and instruction of God is religious and lacking grace! Be informed that grace even more grace is given that we can be able to fulfill the pleasing will of God through Christ in us...
Make you complete in every good work to do his will, working in you that which is well pleasing in his sight, through Jesus Christ; to whom be glory forever and ever. Amen Hebrews 13:21
For this cause we also, since the day we heard it, do not cease to pray for you, and to desire that you might be filled with the knowledge of his will in all wisdom and spiritual understanding; Colossians 1:9
The teaching in Ephesian 2:8-10 shows us the various steps and levels we take while we choose to believe in Christ and the attitude we must have towards Christ on different levels of faith because faith actually grows from one level to another. That's why we have a kind of faith called baby/carnal faith and mature/spiritual faith.
* Paul agrees that people with premature faith are not yet spiritual, they're between God and the world, divided and lack of spiritual knowledge, even unable to take serious the message salvation (They're still socked in the world and need transformation) which is a proccess. Like the lukewarm, sometimes these believers are not even sure whether they really want to follow the Christ they believed. We know it's true because some of us walked like that before.