"Be completely humble and gentle; be patient, bearing with one another in love. Make every effort to keep the unity of the Spirit through the bond of peace. There is one body and one Spirit- just as you were called to one hope when you were called- one Lord, one faith, one baptism; one God and Father of all, who is over all and through all and in all." Eph 4:2-6
But historically what has occurred is a redefinition of the "church" through denominationalism and a spirit of divisiveness which has separated family members from each other. As a reslt many Christians view the "church" as an institution rather than a corporate body of believers. Are you a "member" of that Assembly of God church you attend? While they might deny it, and perhaps you also may deny it, you are indeed a member of that church. You are equally a member of the body of Christ, which is the church, along with every other Christian in your area.
Denominations, such as "The Assembly of God" (and most other institutional churches) however try and make themselves distinct from other assemblies of Christians by emphasizing differences - some particular doctrine such as their take on the "Baptism of the Holy Spirit" or "Speaking in Tongues", which they feel makes their denomination superior to other denominations. But as a result they drive other legitimate Christians out of fellowship with much of the body of Christ.
If you reckon them legitimate Christians then you're going to have to figure out how to get along with them without compromising your convictions. And they are going to have to learn to get along with you as well. I run into such environments myself and as a general rule I try to minister within that environment until I'm driven out or excommunicated. To me it's rather clear what you should do. Consider the circumstances which God has placed you in. Perhaps this very circumstances has come up so that you and they would learn to get along and thus me mutually edified. Perhaps God got sick and tired of their denominational elitist attitude and said to Himself, "I've got to send Chuck over there so they can see that there are other legitimate Christians who believe differently on certain points. And if I can get Chuck to stay, he can show them how to tolerate differences."
I recently had a conversation with a guy about church membership. He seems to think that being an institutional church member is somehow superior to being a ministering non-member, and therefore I should should seek institutional membership. Much as I take issue with him, I actually cannot become an institutional member of the church I presently attend (despite it's claim of being non-denomination) because there's one point of the doctrinal requires I do not meet. (A particular spin on Genesis) But if it's institutional membership which is the priority, rather than love of the brethren, that would mean I would have to break fellowship with the brethren and go wandering around until I found an institutional church in which I met their membership requirements. But by viewing the whole of the Christian community as one corporate body and institutional membership as irrelevant I find I have and promote more a sense of unity on the corporate body as a whole. (Though I may rather tick off denominational types and the institutionally elite. But then again didn't Jesus do that as well?)
Now concerning doctrines such as "Eternal Security" and "The Perseverance of the Saints" I've written some web pages classifying the various points of view which you can view under the theology menu at http://www.bcbsr.com/topics/theo.html
But practically speaking what should be done concerning disagreements over such things. Of course my immediate reaction is "A Bible study based upon proper Biblical Hermeneutics". But in getting along with those of opposing views the best environment I find is a discussion oriented Bible study. When studying the Bible together, even if people come to different conclusions, one can gain respect for opposing views and the Bible gives the sense of how essential such views are. Indoctrination Bible studies - especially topical ones - tend to end up reading particular doctrines into the Bible, or over-inflating the significance of particular denominational doctrines. Indoctrination studies, often lead by church leaders, are not particularly helpful in promoting unity when there are opposing views, as no discussion is allowed. This is the case if Christian's sole source of nourishment is the Sunday morning sermon, (or the "weekly worm" as some call it)
I'm involved in a weekly discussion oriented Bible study at the institutional church I attend. And all three views of Eternal Security and POS are there. One guy has a purely Arminian theology and, like Assembly of God, believes you can lose your salvation. Another has a "Free Grace Theology" who believes in Eternal Security but also that there is not necessarily any correlation between a person's behavior and his salvation status. And there's a number of my point of view (Calvinistic on that particular point) which holds to eternal security and also that there is an inevitable correlation between a person's behavior and their salvation status. And we don't sweep these differences under the rug. But we do respect each other's opinion, even while we try to convert each other to our perspective. We have people in our group ranging from Catholic to independent fundamentalist Baptist and we are very open in discussing our differences and yet we all learn to get along.
One thing that helps is focussing on application. I often say that if the Bible study has no application it has no relevance. For example concerning the conflict over this issue between me and the Arminian guy. I noticed that we have much the same application. I see the Bible saying that while it's "once saved always saved", the feeling of assurance that any particular person actually fits in that category is proportional to the degree he behaves as a child of God should. (1JOhn) The Arminian says you're not saved if you living a lifestyle of sin. Thus the doctrine of "once saved always saved", while true, is no comfort for those behaving signficantly different than Christians should. So you yourself probably have much the same application as the Assembly of God types do concerning the issue of Eternal security. Of course I would point out the problem with the Arminian perspective is that it could logically lead to a legalistic mindset, as it seems that maintaining one's salvation status is a function of one's performance. But not all Arminians view it that way. And thus some non-Arminian Christians might even view that whole community as unsaved in that they could argue that such people have as the object of faith their own works rather than the atoning work of Christ. But that's not actually the point of view of many Arminians. Thus you might engage you brethren there in deeper discussion of these issues.
And by the way, you might as well count it as almost inevitable that you will suffer persecution, most likely by the religious elitist types - the birds which nest in its branches seeking to devour the seed before it gets implanted. That's just part of the Christian life. Jesus came to his own, but his own did not receive him. He was rejected by the elders and chief priests who had him crucified. Such in the Christian life.
In terms of priorities I would treat the church service itself as low priority. Not much fellowship occurs there, but there's opportunity to worship God together and show your face. In the past I've taken issue with pastors over their sermons, but I've kind of given up trying to influence them directly. Instead I associate with those they may reckon the "lowly" -just ordinary Christians, and try to avoid the institutionally elite. (Actually I've broken that rule presently as I've been in a Bible study with a pastor and some other guys weekly. But he's atypical of most pastors I've met - maybe because of his Navigator background - and also the Bible study is discussion oriented) Seek out a discussion oriented Bible study I would say. Or start one yourself. Actually I started a number of them at one church but the institutional leaders made sure to send out letters to their members saying that my Bible studies were not church sponsored.
Or besides Bible study you'll find other ways to love the brethren. That's the objective.