In an article for Va'etchanan 5773, Rabbi Cherki notes that the combination of two different ways to love G-d leads to a love for all mankind.
After "Shema Yisrael – Hear, Israel, our G-d is One G-d" the Torah continues, "And you shall love your G-d with all your heart and with all your soul and with that all you have" [Deuteronomy 6:4-5]. The text in the second paragraph of Shema is different: "And it will be, if you listen to my mitzvot which I give to you today, to love your G-d and to serve Him with all your hearts and all your souls, then I will give you rain in your land ..." [11:13-14]. This is a promise that one who serves G-d with love will be rewarded. In the first paragraph, on the other hand, the demand for love stands alone and is not linked to any reward.
Thus, there are two possible viewpoints of one who serves G-d. One approach is to worship G-d because He is "Our G-d who is One G-d." To love G-d is a natural consequence of the understanding of the words of Shema. And that is why it is written, "with all your heart and all your soul and all that you have." The last word, "me'odecha," is interpreted as meaning, "even if He takes away my money" (see Talmud Yerushalmi Berachot 5:9). A man is ready to give up his wealth out of his great love for G-d.
The second passage takes man's weaknesses into account. A man does indeed serve G-d out of love, but he nonetheless expects to get a reward. Thus, in this second passage the Torah does not add the phrase, "with all that you have" after "with all your hearts and all your souls" because in this case this is not really true. The person wants to increase the value of his possessions and not to ignore them.
As a result of these two different approaches in serving G-d, there is also a third approach which is related to the effect of developing a love for the entire surroundings. It is written, "'Love your G-d' – Cause Him to be beloved by the creatures, like the Patriarch Abraham did." [Sifri]. When a person recognizes that "G-d is One" he lights up with an inner glow which causes other people to love G-d and to say to each other: How pleasant is this person who studied Torah, how pleasant is this person who serves G-d... And they all want to join in the service of G-d.
However, it is not written that one who loves G-d from the point of view of listening "to My mitzvot" causes others to love G-d. Rather, he will receive a physical reward, he will "harvest grains, grapes, and olives" [11:14]. His actions do not lead others to have a greater love of G-d.
"And you shall love your G-d" is one of the halachic sources for the mitzva of converting people and making them Jews. It is written, "You shall love a convert" [Deuteronomy 10:19], in the same way as is written about G-d, "Love your G-d" [11:4]. But this is different from a person born as a Jew, about whom it is written, "Show love to your colleague as yourself" [Leviticus 19:18]. The Rambam explains that the difference is that loving a Jew from birth is motivated by nationalism, which contains some selfish elements. We all grew up in the same family, and we all belong to the same nation. This leads to a natural form of love. Love of a convert is different. It stems from the fact that the convert joined us in our love of G-d, without any prior family links. We have a special kind of love for a convert because he shows us how to love G-d for His own sake.
Source: "AS SHABBAT APPROACHES" – a biweekly column in Shabbat B'Shabbato, Va'etchanan 5773, Volume 1483. (Zomet Institute) See: www.zomet.org.il/eng