Namaste,
The kriyas are effective. It is a science that has been around for thousands of years. How can you doubt if you have not experienced? Try practicing the kriya for 40, 90, or even 1,000 days. You will know.
The majority of yoga is practice, only a little is philosophy.
All that can be said is to practice the kriyas for yourself, to enjoy the happiness, health, peace, and abundance that your discipline brings to you.
all the best
OM
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