Injil bukan ABC, tetapi A-Z Hidup Kristiani

Dulu saya berpikir bahwa berita Injil itu hanya berlaku untuk orang yang belum Kristen (dan mungkin orang Kristen bayi alias petobat baru). Sementara orang Kristen yang mau bertumbuh dalam Kristus harus makan makanan rohani yang keras (yang bukan Injil), yaitu doktrin-doktrin yang sulit. Salah satu theologian-pastor Reformed kontemporer favorit saya, Dr Tim Keller, menolong saya untuk mengerti bahwa semua orang Kristen perlu terus bertumbuh dalam Injil. Berikut kutipan dari salah satu kotbahnya The Prodigal Sons tentang Injil:

"...'the gospel' is not just a way to be saved from the penalty of sin, but is the fundamental dynamic for living the whole Christian life--individually and corporately, privately and publicly. In other words, the gospel is not just for non-Christians, but also for Christians. This means the gospel is not just the A-B-C's but the A to Z of the Christian life. It is not accurate to think 'the gospel' is what saves non-Christians, and then, what matures Christians is trying hard to live according to Biblical principles. It is more accurate to say that we are saved by believing the gospel, and then we are transformed in every part of our mind, heart, and life by believing the gospel more and more deeply as our life goes on." - Tim Keller