The basis for inclusion into Christian fellowship is God's ownership of a person. If God has saved and thereby owns a person, to refuse fellowship with them because of their opinions is to say to God that we do not accept them as a saved person, and we may be held accountable to God for passing such a judgement. Unification is certainly the way forward, keeping in mind, that Christian fellowship is the main mechanism by which we grow unto maturity. Without Christian fellowship, people will remain individuals with erroneous opinions such as that homosexuality is OK. And worse, if such a person attends a "pro-homosexual church", they may never be challenged or change in their belief, because they are like the blind leading the blind. So I suggest that unification between anti-homosexual and pro homosexual believers should be sought, in the hope that the Spirit will prevail in convincing the pro-homosexual believers that their opinion is wrong. And at the same time, the Spirit may temper the attitude of the anti-homosexual believers, to make them more accommodating of those with different views and show the love of Christ a bit more. As the number of denominations has grown over the past hundreds of years, also the number of false doctrines and heresies has grown also. Division, provides a certain environment for false doctrines to emerge - because such doctrines are made in relative isolation, without fellowship with the larger body of Christ.
Jesus was a "friend of sinners", so I'm wondering why two saved people shouldn't be able to fellowship even if they hold a different view regarding a certain matter. A true follower of Christ would be able to fellowship with anyone who bears the name of Christ. If they have received Christ then the fact is they are brothers and sisters in Christ, regardless of their erroneous opinions. If God has owned them, dare we disown them? And it is a function of the church to help correct their erroneous opinions, rather than exclude fellowship or divide into sectarianism. Regarding opinions - the church should not discriminate or exclude those who are "weak in faith". Romans 14:1 says "Welcome the person who is weak in faith—but not in order to argue about differences of opinion."