Is it bad to be a Christian & also believe in reincarnation?

Depends on how 你 are defining "reincarnation."
When we accept 耶稣 into our hearts, the Bible says we are born again.
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John 3:3-7 says:
In reply 耶稣 declared, "I tell 你 the truth, no one can see the kingdom of God unless he is born again."
[Nicodemus speaking]"How can a man be born when he is old?" Nicodemus asked. "Surely he cannot enter a 秒 time into his mother's womb to be born!"
耶稣 answered, "I tell 你 the truth, no one can enter the kingdom of God unless he is born of water and the Spirit. Flesh gives birth to flesh, but the Spirit gives birth to spirit. 你 should not be surprised at my saying, 'You must be born again.'
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In accepting Christ, we are not physically reborn but spiritually.
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Romans 12:2 says:
"Do not conform any longer to the pattern of this world, but be transformed 由 the renewing of your mind. Then 你 will be able to test and approve what God's will is—his good, pleasing and perfect will."
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We are transformed 由 our new outlook on life. Our worldview and understanding of God's will changes us.

So reincarnation, in the definition of a soul being born again into a new body every time the former body perishes, does not coincide with Christianity.

However after the 日 耶稣 comes back for the Christians and the rapture and ending times are over, God will create a new Heaven and a new Earth. And then our spirits/souls will be 给 a new body 由 our Lord.

Hope this helps.

I don't know how christian believe about it, but it is there. 你 have freedom to express what 你 really feel and discuss upon it if it is right 或者 wrong.

It's fine. Some interpretations of the Bible point to reincarnation, and some point in the direction that we only live one life. But who knows? Some sects of 基督教 really embrace reincarnation.

There are some scholars who believe that early Christians did believe in reincarnation but once the Church became established they removed these passages for political purposes. For example in the New Testament when 耶稣 cures the blind man, it is asked if his blindness is caused 由 his own sins our his parents' sins. Since he was blind from birth how could he be responsible for being blind 由 his own sins unless it was from a past life?

In another passage 耶稣 confirms that John the Baptist is the reincarnation of the prophet Elijah:

"The disciples asked:" Why say the scribes that Elijah must come first? "He said:" Elijah is coming to restore all things. But I tell 你 Elijah already came and did not recognize him but did to him what they wanted. Likewise, also the son of man is to suffer from them.. "Then the disciples understood that 耶稣 had spoken about John the Baptist ". (Matthew 17: 10-13, Mark 9. 11-13).

I beleive the Bible and reincarnation are mutually exclusive. Solomon said,"It is apointed once unto man to die, and then the Judgement."
I beleive 耶稣 referred to John the Babist coming in the Spirit of Elijah.

I wouldn't say it's bad to believe in something (With the exceptions of so far child abuse and Satanism), but would that not be a good mixture with Christianity...I honestly don't mind it at all. I'm Christian, and I believe homosexuality is not a sin. So there's also a contrast between the beliefs of Christ and of mine. So to me, it doesn't seem wrong. :)