If church-service attendees are visiting the church because they like and want to hear the pastor, that can be a serious problem for many reasons. But first, I'll say this:
If people are going to church service because they like the pastor, as long as the pastor himself is preaching truth, modeling what it looks like to be surrendered to Jesus, dying to himself, picking up his cross, and following the Lord, eventually the visitor will be convicted by the pastor's life and either want to join him in following Jesus, or decide not to follow Jesus and walk away instead.
But if the pastor is teaching watered-down truths, and being worldly for the sake of not losing any members, then the people he's keeping will not be strong disciples of Jesus who are picking up their cross and following Him. They'll remain people who like Jesus and what He can do for them, rather than people who love Jesus and want to learn how they can please Him.
Sadly, I think many churches are so popular and mega for this very reason. Lots of people like the pastor, enjoy the music, and feel good after leaving service. It's more of an emotional comfort rather than a burning desire to learn more about Jesus and offer themselves to His service. They like what the pastor says, messages that are easy to take in, and that boost self-esteem.
I know this may not always be the case. Francis Chan is one very popular pastor who really preaches and lives out loving and serving Jesus. But, since he doesn't have his own church, it's hard to determine how many people really put to practice Chan's example.
With many mega churches, it's easier to see the fruit, the lifestyle of the members because they are regular attendees of such and such church. When church attendance drops, it's typically because the sermons are more bible-based and thus naturally more convicting, "for the word of God is living and powerful, and sharper than any two-edged sword, piercing even to the division of soul and spirit, and of joints and marrow, and is a discerner of the thoughts and intents of the heart. And there is no creature hidden from His sight, but all things are naked and open to the eyes of Him to whom we must give account.” (Hebrews 4:12-13 NKJV)
But when the sermons are lightly peppered with the bible, and focused more on how much we are loved by God, rather than how much we ought to love Him because He loved us first, the numbers seem to rise.
Let's be honest, it's understandable. People love hearing good things about themselves. It really does release serotonin and dopamine when people compliment and encourage you. Throw in how much the God of the entire universe Himself loves you and it's a whole 'nother level of emotional high.
Now I believe in balance. God is pretty well-balanced. He isn't any one extreme alone. His goodness, truth, holiness, love, wrath, righteousness, wisdom, power; they're all spread out in perfect harmony. That's why when you have pastors who teach about God in this well-balanced way, the churches tend to be smaller. Why? Because Jesus Himself taught that many are called, but only few are chosen, and that wide is the path that leads to destruction, and narrow and difficult is the path that leads to life, and few find it.
When Jesus healed the ten lepers, only one returned. After Jesus was crucified, the many thousands who used to follow Him dwindled to only a hundred and change.
The reality is that a lot of what Jesus says is beautiful and encouraging and esteeming. But a lot of what Jesus says is also difficult, intense, and convicting. Some people realize His love is worth living for, that He is genuinely worthy of all of our devotion. Others, after hearing His more challenging teachings, count the cost and decide they'd rather keep enjoying sin and comfort and so walk away from Him. Again, Jesus taught about this often:
““If anyone comes to Me and does not hate his father and mother, wife and children, brothers and sisters, yes, and his own life also, he cannot be My disciple. And whoever does not bear his cross and come after Me cannot be My disciple. For which of you, intending to build a tower, does not sit down first and count the cost, whether he has enough to finish it — lest, after he has laid the foundation, and is not able to finish, all who see it begin to mock him, saying, ‘This man began to build and was not able to finish’? Or what king, going to make war against another king, does not sit down first and consider whether he is able with ten thousand to meet him who comes against him with twenty thousand? Or else, while the other is still a great way off, he sends a delegation and asks conditions of peace. So likewise, whoever of you does not forsake all that he has cannot be My disciple.” (Luke 14:26-33 NKJV)
Before you get offended, recall who is speaking here: the Creator God, who made you and the ground upon which you stand, and has provided everything you need to still be alive at this very moment. He not only gives you physical life, but He willingly gave up His own life to die the death you and I deserve, that we might be forgiven, accepted, and eternally redeemed. He has every right to command and expect such passionate devotion from His followers. So the real question is: do you agree, and will you choose to surrender to Him?