Is it a sin to force religion on someone?
The New Testament describes persuasion, and Christian history describes worse

In short
The New Testament tells Christians to be ready to explain what they believe, gently and with respect, and describes persuasion rather than pressure. Coercion appears in Christian history at enormous cost and has been widely repudiated. Between the two sits the ordinary difficulty of a parent, a friend, or a spouse who cares.
What the text says
But sanctify the Lord God in your hearts: and be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear:
1 Peter 3:15 was the verse of the day on November 11, 2023. See that day
Often brought in2 Corinthians 5:11
Knowing therefore the terror of the Lord, we persuade men; but we are made manifest unto God; and I trust also are made manifest in your consciences.
Paul says he persuades people. He argues, reasons and pleads throughout Acts - and never once compels.
The counterweightLuke 14:23
And the lord said unto the servant, Go out into the highways and hedges, and compel them to come in, that my house may be filled.
'Compel them to come in' was used for centuries to justify coercion, including by Augustine. It is a line in a parable about a banquet, and reading it as policy did enormous damage.
What Christians agree on
Faith that is coerced is not faith, and every major tradition now says so explicitly. Equally, no tradition treats speaking about belief as itself an imposition.
Where they disagree
Those who stress the duty to speak
Silence about something you believe to be true is not respect. Discomfort is not the same as coercion, and the fear of imposing has quieted a great deal of honest conversation.
Those who stress consent
Repeated pressure on someone who has said no is coercion by another name, particularly where there is a power difference - a parent, an employer, a carer.
Those who focus on the household
Parents are told to raise children in the faith, which necessarily involves teaching before consent. The obligation is real and so is the point at which a child becomes an adult.
Questions worth asking
- Have they asked me to stop, and did I hear it?
- Do I hold something over them - money, approval, a home?
- Am I making a case, or wearing them down?
The distance between offering something and imposing it is usually measured by whether the other person can say no without cost. That is a question about your relationship, and it is answerable.
