Leaving a congregation into which Christ places you is a serious matter. The connection God creates when He makes one a member of a particular body of believers is for life; it is a connection that can be undone only by another act of God.
The only godly reason for a child of God to leave a congregation is when he spiritually outgrows a congregation and God Himself leads him away from it. And if God leads you out of a congregation, you will find you love that first congregation even more after you leave than you did while you were there, even if they have treated you badly, for you will have become more like God than you were before.
Paul is a case in point. After Jesus revealed himself to Paul and he outgrew his fellow unbelieving Jews, this is how he felt toward them:
1. I say the truth in Christ, I lie not, my conscience also bearing me witness in the holy Ghost,
2. that I have great heaviness and continual sorrow in my heart.
3. For I could wish that myself were accursed from Christ for my brethren, my kinsmen according to the flesh
Paul was feeling how Jesus felt toward his fellow Jews who would not believe:
37. O Jerusalem! Jerusalem, who kills the prophets and stones those who are sent to her! How often would I have gathered your children together, as a hen gathers her chicks under her wings, but you would not.
38. Behold! Your house is left to you, desolate.
If you have ever truly outgrown a congregation, this is how you feel toward those you left behind. If you have ever truly matured in Christ to the point that the Spirit would not let you stay among the worshippers with whom you were worshipping, this is how your heart hurts for them. You cannot hate them for not receiving the new and wondrous truths which God let you see; you can only love them and hurt for them.
If you are faithful to Jesus, you will, at some point, outgrow some others in the body of Christ who have not grown as they should. The list of those you outgrow and have to leave behind will include some of the very ones who led you to the Lord, people you regard highly and love very much. This can feel very uncomfortable and confusing for the young soul who experiences it, but if he keeps growing, he will come to see clearly that he has done the right thing.
Remember this, young believer, and let this be the standard for judging yourself in time to come. If you feel contempt for those you have left behind, then you did not outgrow them; you left for an ungodly reason. If you speak evil of them, you have not outgrown them. If you were not open with those you left behind, if you did not testify to them of the truth you saw, you did not outgrow them; you left of your own self-will. If, before you left, you did not humbly and earnestly try to give them something Jesus gave you, then you did not outgrow them, and your leaving was sin.
I repeat: The connection God creates when He makes one a member of a particular body of believers can be undone only by another act of God. For as Jesus said, “What God has joined together, let not man separate.”