Murithi came to the faith in 1989 after being evangelized by a missionary affiliated with Thika Road Baptist Church. The missionary explained the gospel to Murithi through what was referred to as the “Roman Road to Salvation.” Murithi heard and believed the gospel, seeing the depth of his sin and realizing that good works could never atone for his sinful nature. It was at this moment that he called on the name of the Lord, and he believes this was the moment the Lord saved him. He was later baptized at Thika Road Baptist Church as a public demonstration of his trust in the Lord and in obedience to the Scriptures. In the years that followed, he moved from TRBC to attend Pentecostal churches.
Murithi has been married to Wanjiru Mwithia since 2002. Together, they have two children: Mugambi Mwithia (19) and Nyakio Mwithia (16). Over the years, Murithi has developed a deep passion for studying the Word of God and handling it rightly. After several years of searching for a gospel-centered church, God providentially led him and his wife to visit Emmanuel Baptist Church in September 2023. There, they learned that EBC was, within two weeks, going to plant a new church along Kiambu Road, namely, North Point Baptist Church. This was in the vicinity of their home. Murithi and his family have attended North Point Baptist Church since its inception. After completing the membership classes, he and his wife Wanjiru Mwithia were received into membership in December 2023.
Murithi worked for the Government of Kenya for many years, with his last role being at the Ethics and Anti-Corruption Commission, where he headed forensic investigations until 2013. He is now a farmer. On June 15, 2025, North Point Baptist Church voted to call Murithi to serve as one of their elders.