This dates the Bhagavad-Gita to the First or Second Century AD when Jewish missionaries were at work in India. There are, of course, OLDER MATERIALS of Indian origin in the same work, but its compilation must necessarily be later.
The Great Fish takes a big part in the oldest of Hindu thinking, as does Ma-Nu (Noah).
Hinduism does not exist totally unconnected to Western religious currents ~ (NOTE: Hindus, of course, say it's the other way around and that Western religions are not totally unconnected to Hinduism).
There is such a difference in Vedic Yoga and the westernized Yoga, Yoga means yoke, i e Yoked to god and in Hinduism there are over three million gods,
There is the saying, “There is no Yoga without Hinduism and no Hinduism without Yoga.”
So ...with this in mind I can understand how a devout Christian would be concerned.
In a book I read by the Dalai Lama, he said in this carnation he encouraged and discouraged people to stray from the religion they were born into because that religious belief one was born into was the lessons to be learned during this life time,
That is if you believe in reincarnation.
I started doing yoga at age 16, I can stretch with out adding a religious connotation.