Hi, I wnated to know if a sacrament is still effective even if a person has doubts or there heart isnt ‘in it’. I have struggled with lots of doubt, anxiety and paranoia. This results in mixed feelings, which makes my intentions and what I really belive in, hard to discern. I would like to know if I can become a Catholic whilst I am still like this, and live as a catholic like this.
Hi Doubtingseeker,
First I’d like to give a couple of Catholic definitions of a “sacrament”:
A sacrament is an outward sign, instituted by Christ, to give grace.
Here’s a little longer version

from the CCC glossary:
A sacrament is an efficacious sign of grace, instituted by Christ and entrusted to the Church, by which divine life is dispensed to us through the work of the Holy Spirit.
Yes, most sacraments are still effective even if doubt exists. BUT, it’s a qualified “yes”. For those that are still effective, the nature and degree of ones intentions probably affects the amount of grace received. It may even delay reception of that grace. For example:
Baptism - If a person sought Baptism, for whatever ulterior reason, while denying the deity of Christ, Christian truth, no desire to be a Christian, etc., his Baptism would be a true one, however the grace would probably not be present in his soul because he rejects it’s existence and presence. Should he at some later date come to believe, then the Baptismal grace would be present in his soul. **He would not be rebaptized. ** (This assumes the Baptism was done properly.)
Marriage and Confession are sacraments where the intention can definitely invalidate the sacrament.
Marriage: if someone says the marriage vows with no intention of ever carrying them out (lies), the marriage would no doubt be judged as never having taken place - invalid.
Confession: if someone confesses their sin/s to a priest and is not at all sorry, intends to go right on doing it without even trying to stop, their sins are probably unforgiven even tho the priest says the words of absolution. (I say “probably” because only God sees the heart.)
Regarding your becoming a Catholic while still having doubts; it would be best to talk to a priest. To begin with, if you know someone who is a faithful Catholic, you might speak personally with them (if you’re comfortable doing it). They can probably help you and direct you to a priest.
God be with you,
Nita