The book of The Bible where 'love' is mentioned:-
1st-'Song Of Solomon' -24 times
2nd-'1John' -23
3rd-'Psalms' -22
4th-'John' -19
5th-'Deuteronomy' -16
Note that 'John' (the book written by the disciple of love) is 4th on the list .
(Then again, you can prove anything by statistics eg content, context, purpose etc)
It is interesting that Deuteronomy is high up on the list, but it shouldn't be that surprising: given that in Matthew 4, (when being tempted by the Devil), Christ countered Satan by quoting from Deuteronomy 3 out of the 4 times.
Jesus states in the New Testament Matthew 22:37-40 "Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments hang all the law and the prophets."
http://www.biblegateway.com/passage/?search=Matthew%2022:37-40;&version=9;
He also says in John 15:13 "Greater love hath no man than this, that a man lay down his life for his friends." Jesus exemplified this through the atonement when he bled and died for everyone on the earth.
http://www.biblegateway.com/passage/?search=John%2015:13;&version=9;
So I hope I answered your question as to the most important love. The most important love you can have is that you first love your God and second love everyone enough to die for them. However the greatest love there is, is the love Jesus had for all of us when he died for everyone on earth.
psalms
The word heart is found 836 times in the Bible and occurs the most in Proverbs, 85 times
a holy book of sacrament in catholic religion
It could be arguable, but IMO there is no other writing/book in the Bible that expounds upon the depth of God's love as does the Gospel of John. Concerning a human 'love' story, the unique book, 'The Song of Solomon' is most likely the best candidate. In an overall sense though, the entire Bible reflects God's love for all mankind.
Lambs
The bible talks a great deal of love and forgiveness , and so also Jesus taught it . So it is the greatest book of love. The bible mentions love a lot. But i wouldn't call it the greatest book of love because it also tells you to kill homosexuals and to kill people who disrespect their parents. It tells you to rape slaves to death, and a lot of stuff like that. Most Christians actually haven't read the entire bible. Many copies leave out the negative things that are actually part of the book.
figs
Paul the Apostle wrote a letter to the church at Ephesus. The people in this area were called the Ephesians. Many books of the Bible mention Ephesus, but Ephesians in particular says it the most.
The central message of the Bible is the Coming Kingdom of God and the salvation of mankind.
Here are facts. the bible is the most sold book, the most despised book and also the most burnt book in the world.
what book in the bible says the most about christs advent
The longest book of the Bible is Psalms.