Q1. (1 Thessalonians 4:1-2) What is the difference between (1) conducting our lives by rules and (2) conducting our lives trying to please our God?
When we conduct out lives by rules be are restricted and bound by the law - as in the Old Testament. We also fail miserably as did the Israelites. We may start out well, our intentions honourable, but we are weak and fail when doing things in our own strength. When we condutct our lives in a manner pleasing God, we operate on a totally different level. We are filled and motivated by our love for the Lord and His for us. Love is all powerful and comes not from ourselves but from the Lord, and the Holy Spirit empowers us to do things and be the people of God - to be a holy people, things that we cannot do ourselves no matter how sincere nor how hard we try. There is nothing, absolutley nothing stronger than love.
When I thought about this question applying to my life, I realise that if I operate in "rule keeping mode" (which is a habit so easy to fall into as it is a secular way of operating) that any evangelism I try will crash and fall. Maybe that is why so many unbelievers think of Christianity as "thou shalt not's" because too many of us believers operate still in the "rule keeping" mode!
On whose authority does Paul bring these commands?
By the authority of Jesus Christ!