One God

There is one God. He is the Everlasting Father. He is a Spirit.

He robed (manifested) Himself in flesh, born of a woman, to become a substitute for our sins. He came to dwell among His creation in His name of salvation, JESUS. 

"Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved." - Acts 4:12 KJV

"And she shall bring forth a son, and thou shalt call his name JESUS: for he shall save his people from their sins." - Matthew 1:21 KJV 

"To wit, that God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them;" - 2 Corinthians 5:19 KJV

Jesus came to pay the price for our sins so we could be filled with His Spirit. 

He told His disciples, 

"I will not leave you comfortless: I will come to you." - John 14:18 KJV

On the Day of Pentecost, Jesus kept His promise.

"And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance." - Acts 2:4 KJV

Peter preached that day how Jesus came to save us. He then preached HOW we are saved.

"Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost. 

“For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call." - Acts 2:38-39 KJV

"And with many other words did he testify and exhort, saying, Save yourselves from this untoward generation. 

“Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls. 

“And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers 

“…And the Lord added to the church daily such as should be saved." - Acts 2:40-42, 47 KJV