Today's passage (well yesterday's as I write) discusses who the Christ is, but I want to leave this aside and focus on verses 34-40 of Matthew 22. All you need is love.
We all talk about love, the things and people we love. We all have ideas of what love is (oh dear, I now have the Foreigner song in my head), and at various times it confuses us. Often we don't really understand love, confuse it with lust (although to be sure they can go together), and sometimes forget that love is not just a noun to describe our feelings, but a verb describing what we should be doing.
Apparently the Rabbis loved (possibly do still) to debate about the Law (Torah, collection of Old Testament writings) and which was the most important commandment. The Torah are principles for life in covenant Israel. They didn't cover every single situation that might arise, and hence there was a large oral tradition that arose. Despite what some might say, there is a good deal of thinking involved with reading the bible and working out what it means for us and how to live.
Asked for one commandment, Jesus gives two. The first comes from the Shema, the call for Israel to recognise God and love him with their whole being (Deuteronomy 6:4-5). This connects well with the discussion earlier about Caesar and his coin vs God and his image. To love God with our heart, soul and mind is to love God with all that we are, and is how we render to God what is God's. The implications for worship (traditional Christian piety - prayer, bible reading, etc) and holiness (typically the usual emphasis on sexual ethics or what I call pubic Christianity) are obvious. Knowing the bible and some apologetics are also part of loving God with our mind, but only insofar as these things translate into actions.
The call to love neighbour is elsewhere expanded in the parable of the Good Samaritan, which Luke does not include here. The point however, is that love of neighbour cannot be purely spiritual, as indeed neither can love of God - this is an empty idea given we are embodied. Love is therefore embodied. Surely Christ becoming human tells us that.
My neighbour of course is the person I am nearest to. I leave it to you to know how to love that person, since they are your neighbour - but it must be practical. Of course, prayer is practical, but James tells us that when there is a need to be filled we can fill, be the answer to the prayer for the need to be filled. Simples!
It is worth noting that there appears to be no restriction here that neighbour means fellow believer in Jesus as Messiah (in our parlance, Christian). Neighbour means neighbour. Paul said do good to all, especially those in the household of faith (Galatians 6:10) but not only to them.
Good can be done, i.e. I can love directly or indirectly. Sometimes we love our neighbours by supporting a social support network in the form of taxes - and yes there are unemployed with iPhones, fancy shoes etc. Jesus died for sins knowing not all would believe, so I can pay taxes towards unemployment benefits in the knowledge that some will abuse that. That's life.
Indirect good is how I will help my neighbour in a globalised economy and ecosphere who suffers my lifestyle in the form of climate change. My neighbour whose home is sinking beneath the waves may be loved by my taxes going to foreign aid, or campaigning for an immigration deal for environmental refugees (however they arrive), or by lobbying for renewable energy to avoid the harm climate change might do.
So love can be personal or corporate, direct or indirect, local or global. This is the way the world is and we need to embrace the fact that love of neighbour means justice. Indeed, the fact that all people are made in God's image means I love them links these two greatest commandments.
Loving God of course also involves loving all he has made, i.e. caring for creation - but that's a whole other post.