You must seek the church leader (pastor, rabbi or priest) and see what he says. The thinking is a church is deemed a sanctuary and under the protection of God, therefore, weapons are not needed. This is why military color teams sometimes are not armed (and subsequently do not wear hats) for funerals/memorial services. This is not always the case, it depends on the church leader.
Many churches have unarmed drill teams and those teams perform inside the church as well as elsewhere. When it comes to an armed routine, it all depends. Most likely a solo routine will be allowed because it is a display of skill and the church members probably know you and want to encourage you in your hobby.
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