Shul time can be a great time to get to know your kids. To know if they are able to handle shul or not. When kids are still young and don't know how to daven there is no reason for them to have to come to shul. If after going one time to shul with your kids and you see they make noise and don't behave, then realize they are not ready to be in shul. If your child will be able to sit next to you the whole time and not make noise then your child is able to come.
Additionally, shul is not a place for kids to run around and play. Especially if shul's don't have play rooms and the kids end up playing outside by themselves. Its really dangerous to have kids unattended. Its a miracle no one gets hurt.
If the child is mature and can behave in shul then I think it would be a great experience for them. To get to see how their father davens and to get used to shul and want to go when their older.
Also, I don't think mothers should come with all their kids just for the kiddush. It sends the wrong message to the kids. Plus the kids shouldn't take up all the chairs and take food first. Parents should train the kids that they should have respect for the adults and wait their turn to take food, and not to take before davening is over. However, if the kiddish is for somebody who just had a baby or any such simcha then it would be okay for people to come for just the kiddush.
I still remember one time I went to a simcha kiddush, it was buffet style. I was sitting with my family at one table and near us was a young girl with her mother. The young girl got a plate of food and then sat down by her table. Meanwhile the mother was still getting food and hadn't come back yet. The girl waited till her mother returned and started eating, and only then did the girl eat. I was impressed by seeing that, it shows real manners on the girls part, and that she was trained well.
Parshas Netzavim–Vayeilech - *Something to say* *Gather together the people – the men, the women, and the small children (31:12).* In this parshah we learn about the commandment of ...
6 years ago