Who is the person obligated and bound to embrace Islam and act in accordance with its Sharia, and is uttering the Two Testimonies a condition for entering into it?

The accountable individual obligated to embrace Islam and act according to its Shari'ah is the sane, mature person to whom the call of Islam has reached and upon whom the proof has been established. This is because the pen has been lifted from the sleeper until he awakens, from the child until he reaches puberty, and from the insane until he regains his sanity. Allah does not punish anyone except after the message has been conveyed. Uttering the two testimonies of faith is a condition for entering Islam for whoever is able to do so.