The Primacy Of Love As Evidence For The Gospels

I want to quote Craig Keener on the primacy of love in early Christianity, then highlight an implication:

"Nevertheless, other early Jewish movements do not earmark it [love] as paramount with anything like the same sort of consensus found in earliest Christian texts. The role of love as the supreme virtue is distinctive in early Christianity (Gal 5:6; 1 Cor 13:13; Eph 5:2; 1 Pet 1:22; 4:8; 1 John 4:7-21), a distinctiveness that reflects Jesus' own teaching about love as the greatest commandment (Mark 12:29-31). Following Jesus' teaching, various early Christian circles deemed love the heart of the law's instruction for how believers should treat other people, especially among the household of faith (Gal 5:14; Rom 13:8-10; John 13:34-35; Jas 2:8; 1 John 2:7-11, 21; 2 John 5)….early Christians followed especially one teacher [in contrast to the many teachers within Judaism] and thus prioritized his specific teaching." (in Lois K. Fuller Dow, et al., edd., The Language And Literature Of The New Testament [Leiden, The Netherlands: Brill, 2017], 582, n. 63 on 582)

Notice the subtlety of the agreement between the gospels and other early sources in this context. When people are discussing whether the alleged teachings of Jesus found in the gospels are reflected in other early sources, they often focus on more direct and explicit references to his teachings, such as we find in 1 Corinthians 11:23-25. But the letters of Paul, James' letter, and other early sources often reflect the gospels' material in more subtle ways that frequently get overlooked in these discussions.