As background, when the United Church of Canada dealt with the question of human sexuality in 1988 my position was then [and now] opposed to approving homosexuality/bisexuality and to ordaining individuals who are practicing homosexuals/bisexuals. The bible is to be taken seriously, and not lightly dismissed

The question of homosexuality/bisexuality from a christian perspective has at least three separate questions:

a. can an individual be both homosexual/bisexual and a christian
b. should the church approve practicing homosexuality/bisexuality
c. should the church ordain individuals who are practicing homosexuals/bisexuals

My responses:

a. yes, it is possible for a person to be both homosexual/bisexual and a christian
biblically sin is a broken relationship with God; when the word "sin" is used in the singular half the time it is talking about a relationship and not an action
biblically there is no such thing as a big sin or a little sin [though there are a few references in the old and new testaments which talk about a 'great' or 'greater' sin]; society makes a differentiation, but biblically all sin has the same consequences
the only unforgivable sin is to blaspheme the Holy Spirit [mat12:31-32; mar3:28-29; luk12:10; also heb6:4-6; 10:26-27]; which if taken literally would condemn most christians, but see Jesus' treatment of Peter [joh21:15-19] which offers the interpretation that the primary witness of the Holy Spirit is that Jesus Christ is God [see also joh16:8-11, paraphrased to tell us the truth about ourselves, about God, and about who is in control of this world] and there is no other who might reconcile us with God if we reject that witness
the bible says we are all sinners [rom3:23]
so if biblically there are no big sins or little sins, biblically my sin is no different than anyone else's - even the homosexual/bisexual
the difference is not what I do, but what I say about it and what I encourage others to do
b. no, the church should not approve practicing homosexuality/bisexuality; but the church equally should not approve other practices considered acceptable by many christians
but if biblically there are no big sins or little sins, and biblically my sin is no different than anyone else's - even the homosexual/bisexual - then the church would be turfing out a lot of people if sinners were not allowed in [and there might not be anyone left]
I am no more offended that a homosexual/bisexual might have an affair than that a heterosexual might have an affair
not approving homosexuality/bisexuality does not mean these people are outside the walls of the church - they need to be there as much as anyone else
c. the primary pre-requisite of ordination is repentance [1ti3:1-16 has a list, though repentance seems evident; see also mat4:17, mar6:12]
the clergy and laity who in 1988 opposed the ordination of practicing homosexual/bisexual individuals were divided:
the clergy for the most part were opposed not that a person's orientation might be homosexual/bisexual but what they did with it, the laity for the most part were simply opposed that a person's orientation might be homosexual/bisexual
I would prefer a minister with a homosexual/bisexual orientation who said it was wrong to practice homosexuality/bisexuality than a heterosexual minister who said it did not matter

We are not faulted because of our make-up, be it sexual orientation or whatever, but by what we do with it and what we encourage others to do with it.

And, if you take the bible seriously, we are called to be holy by the grace of our Lord Jesus Christ.