Some of the most diligent followers of Christ were the Pharisees. They saw and heard everything that Jesus said and did. They were even more diligent than the apostles. For example, when the apostles forgot that Jesus said He would rise from the dead on the 3rd day the Pharisees remembered. The problem is that their following Jesus did not benefit them, for their motive was not to be His disciples, but criticizers (if there is such a word).
So, today, some of the most faithful congregants may not be there for the correct reason. Some attend every worship service; every meeting, not to be a disciple of Christ, but a criticizer.
According to Ellen G. White, in her book, The Desire of Ages, after a day’s work, Jesus was exhausted and burdened, not from healing the sick or preaching, but from the constant criticism of the Pharisees. So it is today, sometimes, as a leader in the church, your greatest challenges will not come from the work itself, but from those who criticize the work.
"The malicious criticism and misrepresentation with which the Pharisees constantly pursued Him made His labors much more severe and harassing." The Desire of Ages, 333