(1) God is one
1) The Spirit of God is one Spirit
1) The Spirit of Christ is another Spirit (ref. Hebrews 12:9)

(2) God is spirit
2) Yes

(3) The Spirit is one
3) Yes

(4) But you can fellowship with the Father and the Son the one Spirit
You got this worded wrong, here let me fix it…
4) You can fellowship with the Father and the Son in God’s HolySpirit

There, fixed