That would be the religion (worship - way of living) that the one true God states as His requirements for those who believe in Him and who live to please Him.
As Jesus said to a believing Samaritan woman, "The hour comes, and is now, when the true worshippers shall worship the Father in spirit and in truth, for the Father seeks such to worship him. God is Spirit, and they that worship him must worship in spirit and in truth." Jesus then went on to declare that He is the Messiah of God, and He also said that He is "the Way, the Truth, and the Life".
Those who want to know about such eternal matters should read not only the entire 4th chapter of John's gospel but the three chapters preceding it. That will start to open up this vast subject for knowing who Jesus really is is key to unlocking this way of worship that is of the Spirit of God.