Brother Mike put it very well. You can't just pay lip service to God; you cannot fool God, either. He knows your heart and your true motivations. Do you go to church for God or any other reason? Do you tithe for God or for any other reason? Etc. etc.
The lukewarm "Christians" of Revelations 3 (the Laodecian church) are the seeds of the Sower in Matthew 13:22. They have no root in the Word and when riches and cares of the world come, they become unfruitful. As you can see from Revelations 3, He is giving them room to repent. Repent of what? Worldliness and the love of money.
Jesus spoke a lot of the fruits of the righteous, implying that one who truly loves God, loves to do righteousness. Those who truly don't love God are the friends of the world and serve mammon (avarice) over God.