The Bible is the only inspired and authoritative word of God.
The Deity of Christ
His virgin birth, sinless life, miracles, atoning death on the cross, bodily resurrection, bodily ascension, and His personal return in power and glory.
Isaiah 7.14 > Matthew 23 > Matthew 27.42 > Matthew 28.6 > Mark 15.32 > Luke 23.33 > Hebrews 4.13-15 > 2 Corinthians 5.21 > 1 Peter 2.22 > 1 John 3.5 > John 14.1-4 > John 19.18 > John 21.25 > Acts 1.9-11 > Timothy 2.8 > 1 Thessalonians 4.16
There is one God, co-existent in three persons/personalities. Father, Son, and Holy Spirit.
For the salvation of sinful man, the indwelling of the Holy Spirit is essential, that salvation is not gained by human effort, but only through God's grace in the redemption He has provided through Christ, a redemption that is responded to by faith which leads to a life devoted to obeying God.