The simultaneous attacks on Our Lady of Consolation Cathedral and the Protestant Africa Inland Church in the northern town of Garissa were the most recent in a series of incidents since Kenyan troops were sent into Somalia in October to crush al-Shabaab militants.
"These unjustifiable acts of violence being continuously meted out on Kenyans, including women and children, have not only resulted in the loss of innocent lives but also created a sense of insecurity among Christians and all peace loving Kenyans," the bishops said in a statement July 2.
The bishops said they continued to believe the attacks were not part of a religious war even though they were carried out on Christian faith communities.
"We ask all Kenyans to work towards promoting peaceful coexistence," the bishops said.
Witnesses said masked gunmen attacked the churches with gunfire while lobbing hand grenades as worshippers prayed during morning services.
In their statement, signed by Cardinal John Njue, chairman of the Kenya Episcopal Conference, the bishops urged the government to thoroughly investigate the attacks, assess the "country's security situation" and chart a way forward that ensures the safety of all Kenyans.
"We call on all Kenyans to remain vigilant and cooperate with the security agencies and other authorities to ensure their security is guaranteed, we remind them that fighting terrorism, extremism and insecurity is not just for the security agencies but the duty of each and every Kenyan because terrorists and criminals operate amongst us," the statement added.
The bishops also offered their sympathy to the families and friends who lost loved ones in the attack and offered prayers for the injured.
"To Bishop Silas Yego of the African Inland Church and Bishop Paul Darmanin, bishop of the Catholic Diocese of Garissa, we send our condolences and assure them of our closeness to them during these difficult moments," the bishops said.