Hello Aerial and Yogam, 
and thank you for your replies.
I plan to reply to you both at length but, yes, since it is really a complex topic, now I would only like to focus on the “scientific” claim of yoga.
Yogam wrote:
“Yes, yoga is scientific. Because all the effects of the exercises and techniques are described in the classical yoga-scriptures.”
By the same token any classical description in any scriptures (for example the Bible) are to be considered scientific. Just because a description provided in a scripture is about yoga and it includes the term “technique” and because these techniques are to manipulate one’s physical body, breathing and brain, it does not make either the scriptures or the techniques of yoga, or the interpretation of its results any scientific. It is especially NOT proven - either scientifically or otherwise - that these techniques lead to one’s unity with God, and definitely not that these would lead to God faster than other spiritual paths.
The term “science” is simply misused with reference to certain inner, subjective experiences that are derived from artificially triggered mental/physical states and/or from one’s experience resulting from these states.
My point is: it is contradictory to the term “scientific” to claim that these inner experiences - either if data on these are systematically collected or otherwise - would signify any scientific knowledge of someone’s experiencing God’s presence.
Yogam’s metaphor about explaining how an apple tastes actually proves my point. If I report to you guys that right now I am tasting something like an apple, it remains my own isolated, empirical experience and from my report no scientific knowledge could be derived, unless it would be objectively and externally verified that I am actually eating something and what I am eating is actually an apple.
[B]The reliability of my personal report of tasting an apple would be especially doubtful if the very condition of my tasting an apple would first require that I would practise certain yoga techniques that would change my brain cells and would give me physical sensations coming from my altered mind and body state. [/B]
My other point is that my report of eating an apple is objectively verifiable and falsifiable - and that is the very condition to obtain scientific knowledge against any delusion or ignorance - whereas someone’s report of experiencing God is not. In lack of such verification we are left with your faith in my report and I am left with my own experience. [B]Such is the incompatible difference between science and faith[/B], and this significant difference should be also recognised by the advocates of yoga.
The other questions I asked earlier still remain valid. Why and how does Kriya Yoga produce faster results in spiritual development and reaching unity with God than other spiritual paths and how and [B]on what systematic comparisons such claim is scientifically proven? Where is any scientific research to attempt to substantiate such claim? [/B]
I would love to know what you think and to hear the others’ opinion too - form potential Kriya Yoga candidates and from those who have already experienced the effects of it.