Why would a U.S. based non-profit organization put out special Mother’s Day cards just for Muslims?

According to ISLAM Way, celebrating Mother’s Day is NOT permissible for Muslims because it is an innovated festival by non-Muslims which the Prophet and his companions did NOT observe. It is also an imitation of the kuffar (filthy unbelievers) from whom we have been commanded to differ. 

Arab News  A US-based nonprofit group is marking this American Mother’s Day in a special way — by sending greeting cards to Muslim and immigrant mothers. Forward Together is distributing 15,000 customized cards to these mothers across the United States this month, the group told the Huffington Post.

I guess the card below would be a good one to send to your mother if she is one of the four wives of your  Muslim father:

As part of its annual initiative – called Mamas Day – the organization hires artists to depict diverse images of motherhood. This year, in part due to the Trump Administration’s stance on Muslims in the US, the group decided to focus on immigrant and Muslim families.

IslamWay  According to Shaykh Muhamamd ibn Saalih ibn ‘Uthaymeen, “All celebrations which differ from the Eids prescribed in Islam are innovated festivals which may have come from the non-Muslims, in which case as well as being an innovation (bid’ah) they are also an imitation of the enemies of Allah. The festivals which are prescribed in Islam are well known to the Muslims: they are Eid al-Fitr and Eid al-Adha, and the weekly (Eid) of Jumu’ah.”

“There is no other festival in Islam apart from these three. All the festivals that have been invented apart from these are to be rejected because they are innovations and are false according to the laws of Allah, because the Prophet said: «Whoever introduces anything into this matter of ours that is not part of it will have it rejected»,” i.e., it will be thrown back at him and will not be accepted by Allah.

Once this is clear, then it is not permissible to show any of the signs of festivity on the celebration mentioned in the question, namely Mother’s Day. It is not permissible to show joy and happiness, or to offer gifts, and so on.