I'm currently a member of the old order Mennonite Church. I have come to the conclusion recently, upon studying the Bible, that Jesus has asked everyone to be of one mind and there be no divisions at numerous places in his word. I want to leave this group, but they say leaving a church that you were born into and baptized in is a sin against God. How is possible if they are in direct opposition to the ever true and faithful word of God?
An interesting point coming from a group that started as a break-away from Roman Catholicism. By this "rule" people should never have left the Roman Catholic Church because they were born and baptized into that faith.
But the truth is that they would see that as different because they believe Roman Catholicism is wrong -- but that is the point. You realize that the Mennonite Church is not teaching the full truth, so you are looking to find a church whose teachings are closer to the Bible's. Staying in a church that is not teachings God's will would be the sin.
"Do not be unequally yoked together with unbelievers. For what fellowship has righteousness with lawlessness? And what communion has light with darkness? And what accord has Christ with Belial? Or what part has a believer with an unbeliever? And what agreement has the temple of God with idols? For you are the temple of the living God. As God has said: "I will dwell in them and walk among them. I will be their God, and they shall be My people." Therefore "Come out from among them and be separate, says the Lord. Do not touch what is unclean, and I will receive you. I will be a Father to you, and you shall be My sons and daughters, says the LORD Almighty." Therefore, having these promises, beloved, let us cleanse ourselves from all filthiness of the flesh and spirit, perfecting holiness in the fear of God" (II Corinthians 6:14-7:1).
While this passage is talking about separating yourself from unbelievers, it does show the principle that God does not expect people to say among those in the wrong.