Impeachment is the congressional equivalent of a grand jury bringing charges. The next step is a "trial," which is held before the Senate. Unlikely that the Senate would convict Trump.
Remember, Bill Clinton was impeached ... but he wasn't convicted, so he remained in office.
I don't think the Ds would really impeach. What would happen if they succeeded in getting Trump out of office? President Pence, that's what, and he's more of a true conservative Christian than Trump could ever dream of being. President Pence would be the Democrats' worst nightmare. I don't think they really want that, but all the bluster makes for good theater, and rakes in the money.