I occasionally attend Anglican services. My wife is Anglican (as was my late father, though I was brought up Catholic as my parents were married with a dispensation in the Catholic Church).
I do it to pray with her, not to "worship", and she attends Mass with me as well. My conditions for doing so:
-It is not in lieu of Mass; I will fulfill my obligation in a Catholic church;
-I do not make acts of worship there (genuflecting, kneeling, etc.);
-I obviously do not go up for communion;
-I do pray with them, the prayers we hold in common, such as the Creed and the Our Father, or the intercessions.
I do believe that they are gathering in His name; and He did say He would be there when two or three gather in His name. While Anglicanism may be heretical, bear in mind that most people there are NOT guilty of the sin of separation. That sin was done 500+ years ago, and most are simply worshipping the way they were brought up:
818 "However, one cannot charge with the sin of the separation those who at present are born into these communities [that resulted from such separation] and in them are brought up in the faith of Christ, and the Catholic Church accepts them with respect and affection as brothers .... All who have been justified by faith in Baptism are incorporated into Christ; they therefore have a right to be called Christians, and with good reason are accepted as brothers in the Lord by the children of the Catholic Church."
819 "Furthermore, many elements of sanctification and of truth"273 are found outside the visible confines of the Catholic Church: "the written Word of God; the life of grace; faith, hope, and charity, with the other interior gifts of the Holy Spirit, as well as visible elements."274 Christ's Spirit uses these Churches and ecclesial communities as means of salvation, whose power derives from the fullness of grace and truth that Christ has entrusted to the Catholic Church. All these blessings come from Christ and lead to him,275 and are in themselves calls to "Catholic unity."
21 Certain things are required in order to respond adequately to this call:
- prayer in common, because "change of heart and holiness of life, along with public and private prayer for the unity of Christians, should be regarded as the soul of the whole ecumenical movement, and merits the name 'spiritual ecumenism;"'282
(Catechism of the Catholic Church).
That said I'm certainly curious enough to go to a synagogue; not because I have any plan to join but bear in mind that Jesus was Jewish, that they are our "elder brothers", and that much of the Catholic liturgy has its roots in Judaism.
Though Islam interests me from a purely intellectual point of view, going to mosque... less so because I don't understand Arabic.
Keep in mind also that Judaism and Islam worship the same God we do, even though their understanding of Him differs or is incomplete.
It all boils down to our reasons for attending.