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The author is going to do his best to stay within his Calvinistic/Reformed views (which he describes as a "conservative evangelical perspective"), but he is clumsy in doing so, to the point that he violates Scripture and even his own doctrine.
The problem is, he's walking a tightrope. He wants to restrict prayer to a doctrinal system where nothing supernatural is allowed, even as he talks about the Holy Spirit's influence. He's deathly afraid that Charismatics will pray in tongues (1Corinthians 14:14 refers to praying in tongues), but admits there is a supernatural something involved in praying.
So, his general effort is to encourage Christians to pray, but to only go so far.
Lastly, because he generally avoids quoting Scripture, and misrepresents other Scripture, we must deem this Bad Bible Teaching.