Can you help me with this? How do you explain in simple terms the Trinity to some one who is struggling to understand how God, Jesus and the Holy Spirit are different but are also one and the same? Thank you.
I hate to say this, but I am afraid there is no easy and simple answer to the “explanation” of the relationship between the Father, the Son and the Holy Spirit. The church fought over this definition for over four hundred years. If the smartest and best educated followers of Jesus struggled with the meaning of the “trinity,” then we can assume this is no simple question. There are simplified illustrations such as water, ice, steam (very inadequate) and sun, light, heat (not as bad, but still quite inadequate). I am afraid that you will need to go deep with your friend in order for him to get this one. What I propose you do is read John 1:1-18 with him and ask him what Jesus seems to be saying about himself and what John is saying about him. I would especially look at John 1:1 and 1:14 and 18. I would then direct your friend to read the book of John and ask himself if what Jesus claimed about himself supported by what he said and did. Hopefully, he will conclude that it is true what is said about Jesus in John 1, which is that he was in the beginning both God and with God. Hopefully, he will conclude that Jesus is, like John said, the uniquely begotten Son of God, and the source of grace and truth. Once you get these things established, you can move on to Hebrews 1:1-4 and Colossians 1:14f.
Once you establish who Jesus, it will be relatively easy to establish who the Holy Spirit is, as it takes the eye of faith to understand who Jesus is and, once one has faith that Jesus is who he said he is, then when he said that he would send the Holy Spirit, that is a relatively small step.