Most professing Christians would immediately reject an attempt by a loved one to get them to go along with treasonous plot against their country, or a conspiracy to commit murder. In fact they would probably understand that even a dear friend or family member would need to be turned in to the authorities under those circumstances. But while crimes like treason or murder are heinous, they are actually lesser acts than rebelling against God and encouraging your friends and family to join in idolatry and apostasy. Plotting to kill men’s bodies is bad, but plotting to kill their souls is worse.

“Those are certainly our worst enemies that would thrust us from God, our best friend; and whatever draws us to sin, separates between us and God, is a design upon our life, and to be resented accordingly” – Matthew Henry

So, if our loved ones begin to worship false gods or follow false religions, we MUST not follow them. This means that when a husband says to his wife, "let us go to this Mormon church" (or this liberal or Unitarian church, etc.), the wife must reply, "not so, my husband." It means that while a child's duty is to obey his parents, they must not obey if that involves disobeying God. Children, your parents can never lawfully command you to violate God's commandments, and as Jesus tells you, the most important of the Lord's commandments is found in Matthew 22:37-38:

Matthew 22:37 Jesus said to him, " 'You shall love the LORD your God with all your heart, with all your soul, and with all your mind.'38 "This is the first and great commandment.

Often spouses in particular will use your love for them wrongly in this regard saying something along the lines of: If you love me, you’ll do this. But all we have to do to show the falsity of that statement is to unpack it's implications. If we do we will see that what is really being said is “if you love me, you’ll spend eternity in hell with me!” How would that strike you? True love does not lead to the destruction of its object, neither, as Paul puts it, does Love “rejoice in iniquity, but rejoices in the truth”

Remember, as Calvin warns - "God declares that all our tenderest affections, which are implanted in us by nature, and in which all the best persons sometimes indulge, are sinful, if they hinder us from vindicating His glory."