NAIROBI - Pope Francis steps onto African soil for the first time on Wednesday to address the continent's fast-growing Catholic congregation during a trip that will test his ability to bridge faultlines between Christians and Muslims.The Nov. 25-30 tour starts in Kenya and Uganda, which have both seen Islamist militant attacks, before he travels to the Central African Republic, a nation torn by Muslim-Christian strife.He is due to arrive in Nairobi at about 5 p.m. (1400 GMT)."We are living at a time when religious believers, and persons of goodwill everywhere are called to foster mutual understanding and respect, and to support each other as members of our one human family," the pope said in a pre-trip message.Millions of Christians - Catholics and others - are expected to turn out in welcome and for public celebrations of Mass, presenting a challenge for national security forces to keep the pontiff safe and control the huge crowds.Africa's Catholic church is growing fast with an estimated 200 million adherents in 2012, a figure expected to reach half a billion in 2050. In Kenya, about 30 percent of the 45 million population are baptized Catholics, including President Uhuru Kenyatta."We are ready to receive him," Kenya's inspector general of police, Joseph Boinnet, told reporters. "Security arrangements have been put in place, right from arrival."He did not say how many police would be deployed in the capital for the visit, which includes Mass at the University of Nairobi on Thursday, now declared a national holiday. Kenyan media has said at least 10,000 officers would be involved.