Theoretical knowledge can not touch heart without Humility
Substance of Bhakti is Surrender and Humility.
Arrogance repels the Lord; humility attracts the Lord.
Even if you have done no wrong, no mistake in the last 50 years, remember the mistake you did 51 years ago and repent for it and become humble.
Japa, Bhajana and Kirtana are superficial to the extent that we are not humble.
Bhakti and Humility cannot be separated like sweetness cannot be separated from sweet.