The thing about conversation is that even if you develop a genuine interest in people (and therefore can be interested in what they want to talk about), you still can't possibly be genuinely interested in everything. Part of being human is being different from other humans. Part of being a creature made in the image of God is that you reflect not some static and uni-dimensional image in total conformity to everyone else, but that you reflect some aspect of that image like one face of a multi-faced prism. You are created unique. You do have certain likes and dislikes, strengths and weaknesses, personality quirks and hobbies, and there is no sense denying that. It is what you bring to the table.
And so in a conversation, while it is a good thing to find a way to be interested in others and to develop a listening ear and an open heart to different people, you can't pretend you are something you are not. The goal is not assimilation. The goal is not enmeshment of personalities. The goal is not for me to become an avid fisherman and deny that more truly I am an avid cinephile, music lover, or NFL fan. The goal is community. And as Miroslav Volf says in his important book, Exclusion and Embrace, in order to have community you must have difference between individuals. There must be a distance between you so that there is space to receive the other.
The thing is that community is more than just a gathering of people with like interests. It needs to include that, of course, but is not reducible to that. Let's not pretend that community denies the importance of finding people to hang out with and talk to who do have like interests. For all I've said about being interested in what others are talking about, I must also pause to recognize the reality that an integral part of conversation is in fact a search for like interests.
So if I'm getting to know someone who can't stop talking about horticulture---and I'm showing interest not because I could give half a crap about horticulture but because I care to find out about what makes them tick---we may be practicing genuine community to a certain degree but at some point it will cease to be genuine (and will therefore cease to be true community) if I am perpetually pretending to be "turned on" by horticulture.
Now, let's face reality honestly. If we only have a five minute window in which to spark a relationship or have a conversation, I am going to have to face the fact that in that window I must: a) show interest in the person, and b) also find a way to convey my own self in an authentic way. Otherwise we will be in danger of perpetuating a one-sided and phony relationship. This is only measurable over time and can't rise and fall on every single short conversation, but is a reality nonetheless.
The sad fact is that many people will talk your ear off forever without a concern for discovering common interests. In other words, they will rely on your commitment to community for the development of that friendship. At some point, if you are going to experience genuine community, let alone enjoy a friendship within that community (which isn't necessary, but is worth remaining open to), you are going to have to find a way to interject and say something like: "Wow, I'm not much of a horticulturalist myself but I can see why that interests you."
If they ask what does interest you and in the course of time you do find that you have some common interests (or are able to develop them), then you might be able to have a friendship. If you discover you have very few common interests, your friendship might not involve a lot of extra-curricular activity, but that's okay. These things don't need to be forced, unless you are two people stranded on a desert island or you are in a stage of life where one of you really needs a friend.
But if you discover you have no common interests you should still be able to have community. And within the church this should always be possible because of our common belief that human beings are made in the image of God and because of our commitment to self-giving love in the name of Jesus Christ.
I'm not saying that church foyer-talk isn't going to involve a search for common interests. I'm just saying that a church that is built upon common interests is less of a church and more of a club. Clubs are fine. In fact, I think it vitally important to find a "club" (or friendship based on common interests) within a church. But let's not confuse one with the other.