The short answer
Yes: as a single parent, you can use Christian Love Story, a free Christian dating site. Say in your introduction that you have children: the people who write to you know it from the start.
Saying it from the start
Your introduction is the right place to talk about your children: their place in your life, and what you hope for your future family. Your profile also states whether you would like more children (yes, open to it, or no / not anymore). All of this avoids disappointment on both sides.
Protecting your children
Your photo should show you. Don't post photos of your children, and don't share their names or their school early in a conversation. Take time to know the person before introducing them to your family.
Signing up takes a few minutes
All you need is a photo that shows your face, a few honest lines about your faith and what you are looking for, your denomination and your situation. Every photo is checked before it is shown, and a person decides in case of doubt. Creating a profile, browsing members, writing and replying cost nothing, with no subscription and no card to enter.
Moving forward with confidence
Take time to talk on the site before you meet. For a first meeting, choose a public place in daytime and tell someone close to you. A sincere person will never ask you for money. Any member can report a profile, and a charter forbids pressure and inappropriate language.
FAQ
Can I sign up if I have children?
Of course. Christian Love Story welcomes all Christian singles. Talk about your children in your introduction, and state whether you would like more.
Should I post a photo of my children?
No. Your photo should show you. For safety, don't share information about your children early in a conversation.
When should I introduce someone to my children?
When you know them well and the relationship is serious. Start by talking on the site, then meet alone, in a public place.
Is it paid for men?
No. On Christian Love Story, men and women have the same rights and the same price: zero. Creating a profile, reading profiles, writing and replying are free for everyone.
How do I stay safe?
Talk on the site before meeting, meet in a public place and tell someone close to you. Never send money, and report any suspicious profile.