John Lennon is often associated with spiritualism, rather than organized religion. However, that does not mean he was an atheist. A few months before his death, Lennon said in an interview:
“I’m religious in the sense of [admitting there is] more to it than meets the eye. I’m certainly not an atheist. There is more that we still could know. I think this magic is just a way of saying science we don’t know yet or we haven’t explored yet. That’s not anti-religious at all.”
On Christianity, in particular, Lennon also had comments:
“Read Christ’s words, read Buddha’s words, any of the great words. But we don’t need the imagery and the ‘Thou must worship like me or die.’ People got the image I was anti-Christ or anti-religion. I’m not at all. I’m a most religious fellow.”
Sources:
What John Lennon Said About Jesus Just Before the Beatle Died (msn.com)