What is the most important teaching in the Bible?

Many teachings, equally important and inter-related, were learned by one who knew God so well he wrote: "I shall always have hope, I shall always praise you more and more. My mouth will tell of your righteousness, of your salvation all day long, though I know not its measure. I will come and proclaim your mighty acts, O Sovereign Lord; I will proclaim your righteousness, yours alone. Since my youth, O God, you have taught me, and to this day I declare your marvellous deeds... Your righteousness reaches to the skies, O God, you who have done great things. Who, O God, is like you?" (Psalm 71:14-19)

Teachings alone don't do anything, unless people take those teachings to heart and learn lessons from them, as did King David.  In that quote he links God's righteousness, His salvation, His sovereignty, His mighty acts and uniqueness into lessons learned, experientially - not just intellectually. He had learned to hope in, and praise God, always because of those biblical teachings about God.

Mark:12
30. And thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind, and with all thy strength: this is the first commandment.
31. And the second is like, namely this, Thou shalt love thy neighbour as thyself. There is NONE other commandment GREATER than these.      

The gospel or good news message of Jesus Christ that even though we are all sinners, we can be saved by God's mercy and grace and be saved, if we are willing to be humble and repent of our sins and receive and follow Jesus Christ in future.  That's a brief summary of the gospel message of course, that we must be born again and converted, but that's the most important message of the Bible because without God as our Saviour through Jesus Christ who died on the Cross to save us, we have nothing but empty words.

The Bible teaches us that "God is love." ( 1 John 4:8) Everything God does is motivated by love. So we love because God loves.  
Love is long-suffering and kind. Love is not jealous, it does not brag, does not get puffed up, does not behave indecently, does not look for its own interests, does not become provoked. It does not keep account of the injury. It does not rejoice over unrighteousness, but rejoices with the truth. It bears all things, believes all things, hopes all things, endures all things.”​—1Co 13:4-7.

Lord Jesus Christ answers for all of us in , , , , ,

Matt 22:37 Jesus replied: “‘Love the Lord your God with all your heart and with all your soul and with all your mind.’ This is the first and greatest commandment. And the second is like it: ‘Love your neighbor as yourself.’ All the Law and the Prophets hang on these two commandments." 

Amen ! 

Matthew 5 : 48 Greek text .

Matthew 22:37, 38

The first and greatest commandment states to love God with all our hearts, souls, minds and might.


JESUS SPEAKING


Matthew 22:36-40 KJV — Master, which is the greatest commandment in the law? Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments hang all the law and the prophets.

Love thy neighbour as thyself.

The Bible is a book to read, like any other, there is no teaching.