Illegal religion refers to open religious organizations that exist illegally without government approval, as well as various forms of underground religious organizations and religious activities. Most of these organizations carry out activities in the name of nationality, culture, education and charity, which are essentially illegal religious activities.

How to guide family members to resist the infiltration of illegal religious ideas can be started from the following aspects:

1. Learn about illegal religions: You can introduce the knowledge about illegal religions to your family, so that they can understand the dangers and risks of illegal religions, as well as the government's attitude and crackdown on illegal religions. This can make them pay more attention to illegal religions and improve their vigilance.

2. Emphasize the government's crackdown on illegal religions: You can emphasize the government's crackdown on illegal religions to your family and let them know that illegal religious activities are illegal and may cause harm to your family. This can make them trust the government more and increase their vigilance against illegal religions.

3. Guide family members to participate in legal religious activities: Family members can be guided to participate in legal religious activities, such as participating in religious activities approved by the government and participating in religious associations. This will help them understand the significance and value of legitimate religious activities and improve their sense of identity with legitimate religions.

4. Emphasize freedom of religious belief and respect for others' rights: You can emphasize freedom of religious belief and respect for others' rights to your family, and let them know that religious belief is everyone's free choice and should respect others' belief choices. This can make them respect others more and improve their respect for religious beliefs.

In short, it takes patience and care to guide family members to resist the infiltration of illegal religious ideas. It is necessary to introduce the knowledge about illegal religion to family members, emphasize the government's crackdown on illegal religion, guide family members to participate in legal religious activities, and emphasize freedom of religious belief and respect for the rights of others. Only in this way can family members pay more attention to illegal religion, be vigilant and jointly create a healthy family environment.