In his book Knowing God J.I. Packer shares five basic truths that serve as core principles for knowing God:
1. God has spoken to man, and the Bible is His Word, given to us to make us wise unto salvation.
2. God is Lord and King over His world; He rules all things for His own glory, displaying His perfections in all that He does, in order that men and angels may worship and adore Him.
3. God is Savior, active in sovereign love through the Lord Jesus Christ to rescue believers from the guilt and power of sin, to adopt them as His sons, and to bless them accordingly.
4. God is Triune; there are within the Godhead three persons, the Father, the Son and the Holy Ghost; and the work of salvation is one in which all three act together, the Father purposing redemption, the Son securing it, and the Spirit applying it.
5. Godliness means responding to God’s revelation in trust and obedience, faith and worship, prayer and praise, submission and service. Life must be seen and lived in the light of God’s Word. This and nothing else is true religion.
From J.I. Packer in Knowing God, pages 15-16