We can learn from, but cannot live by, the faith of others and so it is up to you to come to your own definition. That definition results from a framework of beliefs. Here I offer mine:
God is Creator, Word, and Holy Spirit – the Trinity – Three in one and one in three., He existed before creation and He is not part of the material universe He created. God is Spirit. He has substance because He exists. His substance existed before, and is different from the material universe He created.
God formed man from the dust (the physical creation) and then breathed His life (the pre- existent Spiritual substance i.e. Himself) into man.
God and man enjoyed a vital dynamic relationship until it was ruined by "the Fall". Restoration of that dynamic and personal relationship could only be accomplished by the actions of a perfect man/kinsman Redeemer
As at the beginning, when God breathed His life into Adam, the Word once more formed life from created matter. This time it was with Mary, and Jesus the Kinsman Redeemer was born
He came. He lived. He demonstrated and taught God's message of love for us. He suffered and died. He rose again, defeating Satan, sin and death. He accomplished the divine exchange and made the fullness of salvation available.
At the feast of Pentecost, the Holy Spirit again came and combined with created flesh. The ekklesia, the called out ones, who form the universal Body of Christ, the 'church', was born. In Jesus' own words they were "born again of the Spirit". He says that we can't enter or even see the kingdom of God unless the Spirit fills us.
It follows then that to live an authentic Christian life and have a vital connection with God, our earthly flesh (i.e. created matter) has to be transformed by the Spirit (the pre-existent Spiritual substance i.e. God Himself)
The Bible is the inspired Word of God but our copies and translations are just dead words. However, when we read them in conjunction with the Holy Spirit, He brings revelation to our regenerated spirit and it is only then that they become alive and the inherent Word of God.
The authentic Christian life is based on:
(1) Being born again by the Holy Spirit.
(2) Accepting that the Bible is the inherent Word of God as revealed by the Holy Spirit.
(3) Giving up all reliance on the world and it's systems for one's health, wealth, and ultimate destination.
(4) Living by faith and trusting in God and relying on Him to meet all your needs according to his Covenant promises as revealed in His Word.
Untold volumes of scholarly works have been written about Christianity and how it applies to the individual. However, for me the four points above state the basic essential understanding upon which any morte detailed discussion has to be based. All else misses the point about Jesus Christ and God's ultimate intentions and purposes.
Authentic Christianity - A definition.