What does “wholehearted” mean?
When the Sh’ma tells us to love God with all our heart, it uses the word l’vavecha with a doubled letter vet. Linguistically it would be adequate to have one vet, making the word lib’cha. But since there are two aspects to the heart, conventionally called the good instinct and the evil instinct, both must be summoned to the love of God.
That’s how one is wholehearted, serving Him with the whole of our heart’s capacities.
Amongst the modern Jewish thinkers there is a difference of opinion – Rav Soloveitchik speaks of polarities, opposing tendencies that both have to be accommodated in our religious life, whilst Rav Kook speaks of things being one without any real conflict between them.
To Rav Soloveitchik there is a tension between opposites; to Rav Kook everything has its place in one overarching whole.