Short answer
A Muslim should not wear a cross, so in the Hanafi view a shirt or kit that clearly shows a cross is makruh tahrimi to wear, and praying in it is disliked. Cover or remove the cross with tape or a patch, or choose a version without it. A plain coloured pattern or a badge with no cross is fine.
Wearing clothing that displays a cross is makruh tahrimi, because the cross is a religious symbol of Christianity, and praying in it is makruh. A design that is only a plus sign, grid or crossing lines is not a cross.
The four schools agree on this.
Explanation
Aisha reported that the Prophet ﷺ did not leave anything in his house that had cross shapes on it without breaking or removing it. The cross stands for the belief that Jesus was crucified, which the Quran denies. So a Muslim does not wear it as a pendant or display it on clothing. The four schools agree on this.
Football kits. Several club badges and national flags include a cross, such as the St George's cross of England, the crosses on Scandinavian flags, and some club crests. Wearing one of these shirts as everyday clothing is disliked, and praying in it is disliked. The simple fix is to cover the cross with tape, a patch or a jacket, or to buy a training top without the badge. Many teams also have away kits or training wear without crosses.
Playing in a team. If your team's kit has a cross and you cannot choose another, cover it where you can. Do not let it stop you from playing a lawful sport. Ask a mufti if your situation is unusual.
Other logos. Kits with sponsors for alcohol, gambling or interest-based lenders are also worth avoiding where you have a choice, since you become a walking advert for them. Images of people or animals on shirts are covered in clothes with pictures.
The evidence
Quran, Surah An-Nisaa 4:157
وَقَوْلِهِمْ إِنَّا قَتَلْنَا ٱلْمَسِيحَ عِيسَى ٱبْنَ مَرْيَمَ رَسُولَ ٱللَّهِ وَمَا قَتَلُوهُ وَمَا صَلَبُوهُ وَلَٰكِن شُبِّهَ لَهُمْ ۚ وَإِنَّ ٱلَّذِينَ ٱخْتَلَفُوا۟ فِيهِ لَفِى شَكٍّۢ مِّنْهُ ۚ مَا لَهُم بِهِۦ مِنْ عِلْمٍ إِلَّا ٱتِّبَاعَ ٱلظَّنِّ ۚ وَمَا قَتَلُوهُ يَقِينًۢا ﴿١٥٧﴾
And [for] their saying, "Indeed, we have killed the Messiah, Jesus, the son of Mary, the messenger of Allah." And they did not kill him, nor did they crucify him; but [another] was made to resemble him to them. And indeed, those who differ over it are in doubt about it. They have no knowledge of it except the following of assumption. And they did not kill him, for certain.
The cross represents a belief that the Quran rejects.
Sahih al-Bukhari 5952
Sahih... لم يكن يترك في بيته شيئا فيه تصاليب إلا نقضه ...
"He did not leave anything in his house with cross shapes on it without breaking it."
Shows the Prophet removed crosses from his surroundings.
Where the ruling is recorded
- al-Durr al-Mukhtar with Radd al-Muhtar, Kitab al-Salah, chapter on what invalidates the prayer and what is disliked in it. Praying in clothing bearing crosses or images is disliked.
- Fatawa Mahmudiyya, Chapter on clothing and adornment. Wearing clothes with religious symbols of other faiths.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.