In today's ecumenical age it is always important to emphasise the need for believers to separate from those who hold false doctrine. We are not to fellowship with those who profess Christianity, yet deny the fundamental truths of God's Word, but are rather we are instructed to 'come out from among them'. Likewise what is necessary on an ecclesiastical level is also important when it comes to our relationship with the world. This is not to be characterised by integration but instead by separation, for although we live in a sinful world, we are not to be partakers of that sin, but are to come apart from it. Biblical separation is good, it is beneficial and it is to practised by all believers, yet it is important that it is practised properly. Our view of separation must never be taken to the point where we isolate ourselves from everyone who disagrees with us when the points of disagreement concern secondary issues.
Each Christian denomination will have its own particular distinctives; truths which, although they do not directly affect fundamental doctrines, are particular to them, and it is right that denominations seeks to preserve these truths within their congregations. This does not mean that we cannot stand alongside other believers where our only differences are those of a secondary nature. Presbyterians can unite with Congregationalists in support of Sabbath observance despite their differences on church government. Baptists can unite with Covenantors in opposition to same sex marriage despite their differences on baptism and psalm signing. Neither group with cast aside its distinctives, nor allow the influence of contrary teaching to permeate their denomination, yet in the pursuit of a greater Christian purpose they can unite with those who hold to the essentials of the faith. A failure to separate from those who hold to damnable heresies is wrong, yet so is it wrong to seclude ourselves from all who will not agree with us on every issue.
It is right that we seek to protect our pulpits from error, and so there are preachers from other congregations in our town whom we would never permit to speak in our church, nor would we speak in theirs. However we must never allow ourselves to think that we alone have the truth. An examination of the historic reformed confessions shows a common truth which exists across denominational divides. The Westminster Confession of Faith 1646 and the Baptist Confession of Faith 1688 are word for word identical in much of their content, showing that the gospel is not restricted to one particular denomination. Where men or churches have departed from their creeds and are guilty of serious compromise on biblical truth, then we can have no fellowship with them, yet let us always remember that there is a biblical unity to be had with those outside our own denomination who are truly of 'like precious faith'.