What does Iman mean? Iman in people's hearts or 6 articles of faith/belief. How can a non-Muslim get an iman in his heart, for example, a Christian believes in the Trinity, not Tawhid; moreover, how can they say shahada before their death? Or is it one of Allah's unseen?

Ustadh AbdulAziz al-Haqqan

I'm not understanding your questions. It is always better to ask one question and give easily understandable details.