An abiding temptation to Christians and the Church is to distort the truth by emphasis. It is a subtle form of disobedience. If the landowner gave his stewards a list of ten responsibilities and they focused on one only, neglecting the other nine. the unfaithfulness and disobedience of the stewards would be apparent to all. But not to the stewards, we suspect. Their uber-faithfulness to one duty would be used to justify the neglect of their other duties.
When Christians overemphasise a responsibility clearly taught in Scripture to the neglect of other commandments their defalcation is usually not immediately apparent to them.
Their zeal for the one commandments often justifies their neglect of the others. At least we are getting the "main things" right, they tell themselves. Our Lord knew all about this deceit of heart. At one point He condemned the Pharisees who focused on less important duties (tithing the produce of the herb garden) whilst they neglected the more weighty matters of the law (justice and mercy and faithfulness, Matthew 23:23). Our Lord said they should have done both: faithfully tithed their herb gardens and faithfully practised justice, mercy, and faithfulness.
In some Christian circles evangelism has become the Most Important Duty--to the eclipsing and neglect of other commandments. One place this shows up is in our worship services. The worship of God has now morphed into an activity with the prime focus being to reach the Unbeliever with the Gospel. Worship has become a means to a "higher" end: gaining converts. Disobedience is the inevitable outcome of such a distortion.
T. David Gordon deliberately understates the outcome to drive the point home:
. . . we can probably agree that a meeting between God and his people becomes very different when those who are self-consciously not his people are invited not only to observe, but to participate and feel comfortable. As a meeting between God and his people, the meeting is compromised. [Why Johnny Can't Sing Hymns (Phillipsburg: P & R Publishing, 2010), p. 152f.]Arguably, worship--public worship--must be considered one of the weighty matters of the law. The first four commandments all address different aspects of worship. How should the Unbeliever "feel" when attending a Christian worship service? Should he or she be invited to observe or participate? The Gentiles during the Jewish disapora in the inter-testamental period attended synagogues as observers; the court of the Gentiles in the temple was likewise to encourage Gentiles to attend and observe, not participate. This is where the God-fearers mentioned in the book of Acts came from: attending, watching, observing and respecting the synagogue services. They were welcomed as observers, not participants.
When the duty to evangelise becomes elevated into the status of an uber-responsibility, worship morphs into an activity centred upon non-Christians, rather than on God meeting with His people. The service of worship must be "seeker friendly" whatever that may mean. Usually it means conducting the service so that non-Christians can participate in the activities of worship. The prayers, songs, music, preaching are all made relevant to non-Christians so they can take part. This is a grave mistake.
Inevitably it means that worship becomes a meeting between God and those not His people, which means in turn that the actual duties and obligations of worship by God's people are neglected.
This always happens when one duty is elevated into an uber-duty--a duty above all duties.