Is it right to attend revivals or meetings held by denominations? Is it right for a member of the church to attend the regular meetings of the denominations? Our appeal should not be to human feelings or thought. We need to go to God's Word to find the answers to these questions (Jeremiah 10:23, Isaiah 55:8-9). We MUST have the attitude of accepting what GOD says in His Word, even if that means we must give up our own ideas.
God has always required His people to be separate. "But I have said unto you, Ye shall inherit their land, and I will give it unto you to possess it, a land that floweth with milk and honey: I am the Lord your God, which have separated you from other people," (Leviticus 20:24). God expected His people to be separated from the religious practices of other nations. He forbade them to intermarry, realizing that to intermarry with idolaters would be to take the chance of being led away from the one true God unto false worship (Solomon is good example). If it could happen to them, would it not be possible for it to happen to us?
We can safely say that idol worship would be a false worship and false doctrine. Further, it may be said that God wants His people to have no part with idol worship. But would that not also be true of any other false religious belief or system? Denominationalism is a false system. It teaches and practices error. What is said in the Bible concerning idolatry, and the fact that God's people should have no part in it must also be said of denominationalism.
I hear, "If I attend a denominational meeting with a friend, then they may attend with me and hear the truth." Is this a valid reason? Are they acceptable to God? "And have no fellowship with the unfruitful works of darkness, but rather reprove them." (Ephesians 5:11). Fellowship is not open to everyone without limitations or restriction; the language of conditionality is especially clear in 1 John 1:7. We are not to participate in, or share in the unfruitful works of darkness. This would include the idea that we are not to encourage, approve, endorse, or support such works, but rather reprove them, expose them (John 3:20). "Now I beseech you, brethren, mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them. For they that are such serve not our Lord Jesus Christ, but their own belly; and by good words and fair speeches deceive the hearts of the simple," (Romans 16:17-18). We are commanded to mark them and avoid them that are contrary to the doctrine. We cannot have fellowship with those who walk in darkness. Those who are outside the light of Christ are not my people to have fellowship with!
Another principle we need to recognize is the fact that God never approves of conversions by compromise. Rather than compromising and saying, "If you attend our meeting, we will attend yours," the Bible says, "Contend earnestly for the faith..." (Jude 3). Not once in the New Testament do we have any example of any New Testament Christian compromising in such a way with God's approval. You simply cannot compromise and contend at the same time. If someone attends our meeting and obeys the gospel as a result of hearing the Word of God, it is not because you compromised and attended with them so that they would attend with you; but, it is in spite of your compromise. God's word is the power to save a soul (Romans 1:16; John 8:32; James 1:21). Compromise has never won a soul to Christ. Rather than compromise to win non-Christians to Christ, the Holy Spirit says it is the manner of life that the Christian lives (1 Peter 3:1-2).
I hope this will stimulate your thinking and study of God's Word. If we want to make heaven our home, we need to think like God thinks and do those things the way God wants!