The Muslim's attitude towards this holiday should be clear: 

1- A Muslim should not celebrate this pagan festival, or join others in their celebrations of it, or attend their celebrations because it is forbidden to celebrate the festivals of non-Muslims. 

Ath-Thahabi said: "If the Christians have a festival and the Jews have a festival, which is peculiar to them, then the Muslim should not join them in that, just as he does not join them in their religion or their direction of prayer."

This is so because the basic principles of the Salf As-salih (the pious predecessors) was Al-walaa' wal-baraa' (loyalty and friendship vs. disavowal and enmity), therefore, it is obligatory for every Muslim to follow this principle. He should love the Muslims and should not follow the non-Muslims; rather, he must be different from them. By doing so, he achieves immeasurable benefits, just as imitating them causes greater harm.
In addition to this, when the Muslims imitate non-Muslims, this makes the latter happy and fills their hearts with joy. If any Muslim girl celebrates this holiday because she sees Margaret or Hilary or whoever does so, then this undoubtedly reflects the fact that she is imitating them and approves of their behavior. But Allah Says (what means): "O you who have believed, do not take the Jews and the Christians as allies. They are [in fact] allies of one another. And whoever is an ally to them among you - then indeed, he is [one] of them. Indeed, Allah guides not the wrongdoing people." [Quran 5:51]

One of the bad effects of imitating them is that this increases their number, as this makes it look as if they have more supporters and followers. How can it be appropriate for a Muslim who recites in every Rak'ah (prayer unit) Allah’s Words (which mean): "Guide us to the Straight Way, The way of those on whom You have bestowed Your Grace, not (the way) of those who earned Your Anger, nor of those who went astray" [Quran 1:6-7], to ask Allah for guidance to the Straight Path of the believers and to keep him away from the path of those who have earned His anger and of those who went astray, and then deliberately follows their path and imitates them?  

Statistics indicate that Valentine's Day is second only to Christmas in popularity. So, it is clear that the Feast of Love is one of the festivals of non-Muslims and that it is second only to the festival of Christmas. So, it is not permissible for Muslims to participate in such celebrations, because we are commanded to differ from them in their religion, customs and other things that exclusively belong to them, as is stated in the Quran, Sunnah (Prophet’s tradition) and scholarly consensus. 

2- A Muslim should not help the non-Muslims in their celebrations because it is one of the rituals of disbelief. Helping them and approving of what they do is helping them to manifest disbelief and make it prevail, and approving of it. The Islamic religion does not allow a Muslim to approve of disbelief or help others to manifest it and make it prevail.

Hence, Ibn Taymiyyah said: "It is not permissible for the Muslims to imitate them in anything that is specifically part of their festivals, whether it is food, clothing, bathing, lighting fires, or changing a custom of daily life or worship."

3- A Muslim should not support other Muslims who celebrate this pagan festival. Rather, it is obligatory to denounce them, because for the Muslims to celebrate the festivals of non-Muslims is an evil action which must be condemned. Ibn Taymiyah said: "Just as we should not imitate them in their festivals, we should not help a Muslim to do that as well; rather, he should be told not to do that."

Based on this, it is not permissible for Muslim businessmen to deal in gifts for Valentine's Day, whether they are particular kinds of clothes, red roses, or whatever. Similarly, it is not permissible for the one who is given a gift on this occasion to accept it, because by accepting it, he is showing approval of this holiday.

Once a Da‘ee (caller to Islam) said: “we went to a flower shop in one of the Muslim countries and we were shocked to find it completely prepared for this occasion, with red carpets at the entrance, red placards and red decorations. We were met by one of the people who worked there, and we asked him why they had done so much to decorate the place for this occasion’”.

He said that these preparations had begun early, and that there had been so many orders… Then he told us that he had been amazed by that, because he was a new Muslim who had left Christianity. He had known about that before he became Muslim, so how come his customers were Muslims and not Christians?

Other shops ran out of red roses, which were being sold at high prices. When one of the Du‘at (female Islamic propagator) entered upon the female students who were gathered in the lecture hall, she was dismayed to find them all carrying something red. One had a red rose, another had a red scarf, or a red handkerchief, or a red bag, or red socks and so on… 

Among the things that have been seen among the Muslims on this holiday:

a- All the female students agreeing with their friends to tie a red ribbon on the right wrist.

b- Wearing something red (a blouse, hair clip, shoes…). This reached such an extent last year that when we entered the classroom found most of the students wearing it, as if it was a uniform.

c- Red balloons on which are written the words "I love you". They usually bring these out at the end of the school day, in an area far from where the teachers can see them.

d- Writing names and hearts on their hands, or just initials.

e- Red roses are widespread on this day.

Groups of girls entered their lecture rooms on February 14, each of them wearing something red, with red heart-shaped stickers on their faces, wearing red make-up. They started to exchange red-colored gifts and kiss one another warmly. This happened in more than one university in the Muslim world, even in an Islamic university. In other words, they were celebrating Saint Valentine's Day.

On that day, secondary schools (high schools) were astonished by the large numbers of female students who brought red roses of the finest quality, colored their faces with red cosmetics, wore red earrings, and started to exchange gifts and warm greetings, in celebration of this day. 

Valentine's Day has come to a number of Arab and Muslim countries, and has even reached the heartland of Islam (the Arabian Peninsula). It has reached societies which we had thought far removed from this insanity. In Riyadh, the price of roses has risen incredibly, to an extent that a single rose costs around 36 Saudi Riyals (approximately10 Dollars), whereas before this day it cost 5 riyals. Gift shops and card shops compete in designing cards and gifts for this occasion, and some families hang up red roses in the windows of their homes on this day.  

In some of the Muslim countries, shopping centers and hotels have organized special celebrations for Valentine's Day. Most of the stores and business places are covered in red. One of the finest Gulf hotels was full of balloons and dolls. Following the customs of the Feast of Love and the pagan myths, one restaurant owner put on a dramatic production with "Cupid", the idol of love in the Roman myths, nearly naked and carrying a bow and arrow. He and his cohorts were looking to select "Mr. & Mrs. Valentine" from among the people present. 

Less expensive restaurants also celebrated this day in their own way. Some stores replaced their regular plates with heart-shaped plates, used red tablecloths and linens, and put a red rose on each table for the man to present to his beloved. 

We must oppose these things by all possible means. The responsibility rests with us all. 

4- We should not accept compliments and wishes on Valentine's Day, because it is not a holiday or an ‘Eed for the Muslims. If the Muslim is congratulated on this occasion, he should not return the congratulation. Ibn Al-Qayyim said: "With regard to congratulating others with the congratulations used by the non-Muslims on such occasions, it is prohibited by scholarly consensus, such as congratulating them on the occasion of their festivals or fasts, wishing them a blessed festival, etc.

Finally, we must explain the true nature of this holiday and other festivals of the non-Muslims to those Muslims who have been deceived by them, and explain to them that it is essential for the Muslim to be distinguished by his religion and to protect his 'Aqeedah (belief) from anything that may damage it. This should be done towards the Ummah (Muslim nation) for the sake of Allah and in fulfillment of the command of enjoining good and forbidding evil.