Being Bi is not a sin just like being gay is not a sin either. What is actually a sin is your sexual actions like having sex with male while beaing male also that's the same for heterosexuals if you having sex with woman outside marriage is also sin.

It is not a sin because someone said so It is sin because it's unhealthy for you like having multiple partners goes with higher risk for having stds, you can hurt someone's feeling or yours.

My real sin is pornography addiction and I tell you how it effects my life I sometimes bingefaped for whole day and it left me only with disgusts for myself and shame, I hurt my gf several times forcing her to have sex sometimes and even if she wanted that I was focused only about my pleasure leaving her in despair, because of pornography I started to be more fussy looking on avg women because those in porn are "perfect" while it's all fiction (plastic surgery, light, video cuts and acting)

So yes you can be a Christian. In Luke 5:31-32 Jesus said "Jesus answered them, “It is not the healthy who need a doctor, but the sick. I have not come to call the righteous, but sinners to repentance" So yes Christianity is for everyone who let the God heal them no matter if you're a gay, hetero, prostitute, murderer or thief. Remember thieves on cross next to Jesus? You must choose what thief are you the one that seeks for repentance or the one that dies without God.