I was recently asked about eternal security. I believe that a true Christian cannot permanently or totally lose his faith (but note those adverbs).
However, I also serve in a denomination that chose, long ago at our founding, not to make belief in eternal security -- or disbelief in it, for that matter -- a breaking-point for fellowship, membership, leadership, or participation in the Lord's Table. This is a sub-set of our decision to be neither an Arminian nor a Calvinist denomination. Can we harmonize these two principles? I think we can.
First is to recognize there are boundaries to our church's doctrinal flexibility. The Free Church is not a liberal church. We have a conservative, Bible-based, Protestant/evangelical statement of faith, and we require adherence to it. You can find it on this website, as well as at www.efca.org. So, even though we want to gather in fellowship around the core basics of the Gospel, and its essential foundations (such as Biblical inspiration and authority), there are definite points where our doctrinal inclusion ends.
One end-point is whether good works justify us of our sins. Good works do not savingly justify us prior to faith in Christ; and they do not savingly justify us after faith in Christ, either. That very idea is condemned by the Lord through Paul back in his letter to the Galatians, specifically Galatians 1:6-8.
Good works are the result and proof of true saving faith (see James 2:18 and following). That proof is to other people; God doesn't need it, He knows our hearts. A good tree always produces some good fruit. The Gospel seed, when it has a true faith-root, always produces a crop of righteous living. Maybe only thirty-fold, but something (see Jesus' parable of the four soils in Matthew 13).
A different, opposing end-point can be found on the pro-eternal-security side. These would be teachings that say it's possible to trust in Christ without repenting of sin; or that faith in Christ doesn't renew the moral nature of the person's heart; or that we can never question a person's profession of faith because of wicked behavior.
Faith in Christ and repentance of sin are two sides of just one coin. Christ died for our sins, specifically, so if we still love our sins we won't be interested in what He did. Faith in Christ causes a new creation, a rebirth of one's self (Romans 6:6). 1st John 3 says that people who walk in righteousness show they have God as their Father, and those who walk in wickedness, like Cain, have Satan as their father.
To use two doctrinal terms, you have legalism perched at one end of the eternal-security issue, and antinomianism (lawlessness) perched at the other end. The first, legalism, contradicts Ephesians 2:8-9. The second, antinomianism, contradicts James 2:14-26.
Neither legalism or antinomianism are okay in the Free Church. But inside those hard boundaries, there's some room to study, think, discuss, and move around.
In practice, this broader approach to church fellowship requires the discipline of courtesy. We can't insult people, or say, "Oh that's a stupid idea!", or roll our eyes at people, when someone says something with which we disagree. We also can't just assume everyone in the room agrees with us. Instead, using courtesy, brother sharpens brother like iron sharpens iron.
We also recognize that pastors and elders also have opinions. An elder is conscience-bound before God to preach or teach what he truly believes a Bible passage says. So, attenders should not get upset if and when a leader preaches something with which they don't agree. This conservative, Gospel-centered breadth of fellowship doesn't mean that leaders have to be muzzled.
I knew an odd, funny case where some new attenders became upset because a baby was baptized during their morning service. But they were attending.... a Presbyterian church! Presbyterians baptize babies. What sort of church did the new attenders think they were? Did they not read the sign outside? An individual church will have distinct teachings and practices. Each person will need to pray and think through what they can live with, you might say.
However, I do think it's possible to preach on disputed secondary topics. One way is not to overdo it. A church that feels like it has to mention predestination or tongues every week is, in my opinion, imbalanced. A second tactic is to teach truths without hammering on the people. It's also important to characterize other views fairly, and not ridicule them. Courtesy goes a long way, in this regard.
I believe in eternal security (I think the Lord has helped me build a little more nuanced view than what I was taught as a young Christian), and at the same time we have members who do not. If you are interested in the teachings of the Free Church, I encourage you to read our statement of faith, located here on our website.