In answer to your question, yes I believe I have access to the Holy Spirit too. If I did not I wouldn't care about the truth of the gospel, nor would I be able to say "Jesus is Lord" and truly mean it. The proof is in the pudding, so to speak, or as the Bible says, "you will know them by their fruits".
Before I committed my life to Christ I did believe in one God. I didn't know who God really was, but I believed, and I was a miserable wreck of a person. The only thing that kept me from ending my life was the belief I had deep in my heart that I was not saved, and fear of God's wrath. But God changed all that through Christ. If I didn't have the Holy Spirit, how could I share in eternal life? This is what the Bible reads: Romans 8:11: "But if the Spirit of him that raised up Jesus from the dead dwell in you, he that raised up Christ from the dead shall also quicken your mortal bodies by his Spirit that dwelleth in you."
I have also found several scriptures that indicate that believers receive the Holy Spirit, unless these are interpreted incorrectly in my translation of the Bible. Those are: Luke 11:13, John 7:39, 1 Corinthians 12:3, Ephesians 1:13, Ephesians 4:30, and 1 Thess. 4:8. Given more time I believe I could find others.
So what about now, do I preach lies, hatred? That is not my intention at all. It is not my place to condemn anyone to hell or decide who is to be saved and who isn't. I am not sure that Muslims are saved, perhaps I will never know until the very end. But I do have a real problem with using the "all gods are one" logic to eliminate the NEED for preaching the gospel of Christ to the ends of the earth, even to Muslims.
As for belief in one God, that is monotheism, not necessarily Christianity. Buddha, for example, was a man. While he was living, he spoke of peace and kindness, but he did not ask his followers to worship him. He died, and his image was made into golden statues. To worship a man or a statue instead of the living God, how could that be anything but idol worship? It is not the same as Christian worship since Jesus and God the Father are one. Our God, therefore, I cannot imagine that He is not jealous over those who pray to Buddha, even if they do some good in the world.
The thing that struck me the most was what Jesus said in Matthew 7:13 Enter ye in at the strait gate: for wide is the gate, and broad is the way, that leadeth to destruction, and many there be which go in thereat °: Matthew 7:14 Because strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it.
There isn't exactly only a "few" that believe in God, now is there? But there are a few that know Christ and follow him, and even fewer that believe that He and the Father are one. Besides, doesn't everyone deserve the opportunity to know and to fellowship with Christ? I know it is the most precious thing in my life, how about you?
Well I have a lot more I could say on this but it is 1:30a.m. and my baby is about to wake up at any time now. Had a lot of fun looking all of this up, actually, thank you for giving me an excuse to.