Sorry, but Paul did not say that "the next moment" is when the dead are with God, that is your conclusion, because you are ignoring the third state Paul speaks of: being naked and unclothed. He spoke of this "naked state" between the earthly body and the glorious body where we are without a body (in the grave) - a state which he says we groan with desire to bypass and go to be with God in our glorious body. If we go straight to God at death, then why does Paul say we groan with desire to not be without a body and naked? Why would he, or any Christian, give a care about that if we're immediately in heaven at death? Because Paul knew what Job said - that he would be in the grave where his body would be eaten of worms as he waited for the 7 last plagues of wrath to pass after which Jesus would call upon him to rise with new, glorious flesh and be with Him.
Verse 4 "For we that are in [this] tabernacle do groan, being burdened: not for that we would be unclothed, but clothed upon, that mortality might be swallowed up of life."
Verse 6 is simply stating that the Spirit by faith gives us confidence in the promise that one day we'll be with Him, though we are absent from Him now in this earthly body.
Then what is your interpretation of where a Christian believer goes at death. Where does his body and his spirit go?