I'm listening to the Zombies' album New World, and for the first time, I noticed the expansion in the a cappella part at the beginning of "Heaven's Gate." The first few lines ("And now Heaven's gate is open wide / For you have put a light inside me / I can see that Heaven is near") are mostly centered, but the next line ("Heaven is here") is spread throughout the stereo channels.
That stereo expansion and the instrumentation's coming in only after that a cappella introduction both serve to further what's in the lyrics - the feeling of arrival at the titular Heaven's gate.
Furthermore, the drumming pattern is similar to that on "She's Not There." Like I've said before, I'm not a drummer, and I don't know the terminology, but both songs have two drum hits followed by a cymbal crash (although I think "She's Not There" uses a snare and "Heaven's Gate" doesn't). It's important to note that I'm referencing the stereo version of "She's Not There." The mono version has an overdubbed drum part. However, the drum part during the choruses of "Heaven's Gate" (and at the very end) sounds a bit like the overdubbed version of "She's Not There," with the extra drum beat. In any case, it's interesting that Hugh Grundy's drumming retained that characteristic element.